| OT | objective test; oblique talus; occlusion time; occupational therapist, occupational therapy; ocular ... |
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| OX | optic chiasma; oxacillin; oxalate; oxide; orthopedic examination; oxytocin |
| PION | posterior ischemic optic neuropathy |
| POA | pancreatic oncofetal antigen; phalangeal osteoarthritis; preoptic area; primary optic atrophy |
| SOD | septo-optic dysplasia; superoxide dismutase |
| posterior ligament of head of fibula | A ligament uniting the posterior part of the head of the fibula to the tibia. Synonym: ligamentum capitis fibulae posterius. (05 Mar 2000) |
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| crown of head | The topmost part of the head. Synonym: crown of head. (05 Mar 2000) |
| head | 1. To be at the head of; to put one's self at the head of; to lead; to direct; to act as leader to; as, to head an army, an expedition, or a riot. 2. To form a head to; to fit or furnish with a head; as, to head a nail. 3. To behead; to decapitate. 4. To cut off the top of; to lop off; as, to head trees. 5. To go in front of; to get in the front of, so as to hinder or stop; to oppose; hence, to check or restrain; as, to head a drove of cattle; to head a person; the wind heads a ship. 6. To set on the head; as, to head a cask. To head off, to intercept; to get before; as, an officer heads off a thief who is escaping. To head up, to close, as a cask or barrel, by fitting a head to. Origin: Headed; Heading. 1. The anterior or superior part of an animal, containing the brain, or chief ganglia of the nervous system, the mouth, and in the higher animals, the chief sensory organs; poll; cephalon. 2. The uppermost, foremost, or most important part of an inanimate object; such a part as may be considered to resemble the head of an animal; often, also, the larger, thicker, or heavier part or extremity, in distinction from the smaller or thinner part, or from the point or edge; as, the head of a cane, a nail, a spear, an ax, a mast, a sail, a ship; that which covers and closes the top or the end of a hollow vessel; as, the head of a cask or a steam boiler. 3. The place where the head should go; as, the head of a bed, of a grave, etc.; the head of a carriage, that is, the hood which covers the head. 4. The most prominent or important member of any organised body; the chief; the leader; as, the head of a college, a school, a church, a state, and the like. "Their princes and heads." "The heads of the chief sects of philosophy." (Tillotson) "Your head I him appoint." (Milton) 5. The place or honor, or of command; the most important or foremost position; the front; as, the head of the table; the head of a column of soldiers. "An army of fourscore thousand troops, with the duke Marlborough at the head of them." (Addison) 6. Each one among many; an individual; often used in a plural sense; as, a thousand head of cattle. "It there be six millions of people, there are about four acres for every head." (Graunt) 7. The seat of the intellect; the brain; the understanding; the mental faculties; as, a good head, that is, a good mind; it never entered his head, it did not occur to him; of his own head, of his own thought or will. "Men who had lost both head and heart." (Macaulay) 8. The source, fountain, spring, or beginning, as of a stream or river; as, the head of the Nile; hence, the altitude of the source, or the height of the surface, as of water, above a given place, as above an orifice at which it issues, and the pressure resulting from the height or from motion; sometimes also, the quantity in reserve; as, a mill or reservoir has a good head of water, or ten feet head; also, that part of a gulf or bay most remote from the outlet or the sea. 9. A headland; a promontory; as, Gay Head. 10. A separate part, or topic, of a discourse; a theme to be expanded; a subdivision; as, the heads of a sermon. 11. Culminating point or crisis; hence, strength; force; height. "Ere foul sin, gathering head, shall break into corruption." (Shak) "The indisposition which has long hung upon me, is at last grown to such a head, that it must quickly make an end of me or of itself." (Addison) 12. Power; armed force. "My lord, my lord, the French have gathered head." (Shak) 13. A headdress; a covering of the head; as, a laced head; a head of hair. 14. An ear of wheat, barley, or of one of the other small cereals. 15. <botany> A dense cluster of flowers, as in clover, daisies, thistles; a capitulum. A dense, compact mass of leaves, as in a cabbage or a lettuce plant. 16. The antlers of a deer. 17. A rounded mass of foam which rises on a pot of beer or other effervescing liquor. 18. Tiles laid at the eaves of a house. Head is often used adjectively or in self-explaining combinations; as, head gear or headgear, head rest. Cf. Head, A buck of the first head, a male fallow deer in its fifth year, when it attains its complete set of antlers. By the head. <anatomy> The most anterior of the three pairs of embryonic renal organs developed in most vertebrates the pronephors. Head money, a capitation tax; a poll tax. Head pence, a poll tax. Head sea, a sea that meets the head of a vessel or rolls against her course. Head and shoulders. By force; violently; as, to drag one, head and shoulders. "They bring in every figure of speech, head and shoulders." . By the height of the head and shoulders; hence, by a great degree or space; by far; much; as, he is head and shoulders above them. Head or tail, this side or that side; this thing or that; a phrase used in throwing a coin to decide a choice, guestion, or stake, head being the side of the coin bearing the effigy or principal figure (or, in case there is no head or face on either side, that side which has the date on it), and tail the other side. Neither head nor tail, neither beginning nor end; neither this thing nor that; nothing distinct or definite; a phrase used in speaking of what is indefinite or confused; as, they made neither head nor tail of the matter. Head wind, a wind that blows in a direction opposite the vessel's course. Out one's own head, according to one's own idea; without advice or cooperation of another. Over the head of, beyond the comprehension of. To be out of one's head, to be temporarily insane. To come or draw to a head. See Come, Draw. To give (one) the head, or To give head, to let go, or to give up, control; to free from restraint; to give license. "He gave his able horse the head." . "He has so long given his unruly passions their head." . To his head, before his face. "An uncivil answer from a son to a father, from an obliged person to a benefactor, is a greater indecency than if an enemy should storm his house or revile him to his head." . To lay heads together, to consult; to conspire. To lose one's head, to lose presence of mind. To make head, or To make head against, to resist with success; to advance. To show one's head, to appear. To turn head, to turn the face or front. "The ravishers turn head, the fight renews." . Origin: OE. Hed, heved, heaved, AS. Heafod; akin to D. Hoofd, OHG. Houbit, G. Haupt, Icel. Hofu, Sw. Hufvud, Dan. Hoved, Goth. Haubip. The word does not corresponds regularly to L. Caput head (cf. E. Chief, Cadet, Capital), and its origin is unknown. Source: Websters Dictionary (01 Mar 1998) |
| head and neck neoplasms | Neoplasms of the head and neck. (12 Dec 1998) |
| head-bobbing doll syndrome | <syndrome> Bobbing motion of the head usually due to cysts in or about the third ventricle. (05 Mar 2000) |
| head botflies | Flesh flies of the dipterous families Oestridae and Cuterebridae; robust, hairy, black, yellow, or gray flies that, while flying, deposit newly hatched larvae or, in some cases, eggs, on or near the nostrils of sheep, goats, deer, horses, camels, and, rarely, man. (05 Mar 2000) |
| head cap | A collapsed membranous vesicle that covers the anterior part of the nucleus of the spermatozoon, derived from the acrosomal granule; the carbohydrate-rich substance of the cap is associated with hydrolytic enzymes that aid in sperm penetration of the zona pellucida of the ovum. Synonym: head cap. (05 Mar 2000) |
| head cavity | The cephalic region in the embryos of vertebrates containing the modified somites that give rise to the extrinsic eye muscles. (05 Mar 2000) |
| head-down tilt | Posture while lying with the head lower than the rest of the body. Extended time in this position is associated with temporary physiologic disturbances. (12 Dec 1998) |
| head-dropping test | A test used in the diagnosis of disease of the extrapyramidal or striatal system (e.g., parkinsonism, Wilson's disease); with the patient supine, relaxed, and his attention diverted, the examiner briskly lifts the patient's head with the right hand and then allows it to drop upon the palm of his left hand; the head of a normal person drops suddenly like a dead weight, whereas, in striatal disease the head falls slowly, gently, and almost hesitantly. (05 Mar 2000) |
| head fold | A ventral folding of the cephalic extremity in the embryonic disk, so that the brain lies rostrad to the mouth and pericardium. (05 Mar 2000) |
| head injuries | General or unspecified injuries involving the head. (12 Dec 1998) |
| head injuries, closed | Organic or functional damage resulting from trauma to the head where continuity of the scalp and mucous membranes is maintained. When brain injury results from closed head injuries, the primary cause is mechanical stretching and shearing of nerve fibres. Also common are focal intracranial lesions including haematomas and contusions. (12 Dec 1998) |
| head injury | Refers to a group of head injuries ranging from minor to major. Examples include scalp contusion, scalp haematoma, concussion, brain contusion, skull fracture, epidural haematoma, intracerebral haemorrhage, subarachnoid haemorrhage and subdural haematoma. Features shared by all head injuries (serious and nonserious) include: dizziness, nausea, vomiting, giddiness, sleepiness and headache. More serious features include: protracted vomiting, lethargy, difficulty waking up, loss of consciousness, seizure, confusion, change in mentation or coma. (27 Sep 1997) |
| head kidney | 1. The definitive excretory organ of primitive fishes. Synonym: head kidney. 2. In the embryos of higher vertebrates, a vestigial structure consisting of a series of tortuous tubules emptying into the cloaca by way of the primary nephric duct; in the human embryo, the pronephros is a very rudimentary and temporary structure, followed by the mesonephros and still later by the metanephros. Synonym: forekidney, primordial kidney. Origin: pro-+ G. Nephros, kidney (05 Mar 2000) |