| semipenniform | <anatomy> Half or partially penniform; as, a semipenniform muscle. Source: Websters Dictionary (01 Mar 1998) |
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| semipermeable | Freely permeable to water (or other solvent) but relatively impermeable to solutes. Depending on the context, it has been used to imply impermeability to all solutes except very small uncharged molecules (e.g., a cell membrane), or merely impermeability to very large molecules such as proteins (e.g., a capillary membrane). (05 Mar 2000) |
| semipermeable membrane | <biology, physiology> A membrane that is selectively permeable to only one (or a few) solutes. The potential developed across a membrane permeable to only one ionic species is given by the Nernst equation for the species: this is the basis for the operation of ion selective electrodes. (18 Nov 1997) |
| semiphlogisticated | <chemistry> Partially impregnated with phlogiston. Source: Websters Dictionary (01 Mar 1998) |
| semiplacenta | The type of placenta in ruminants, horse and pig, in which the maternal and foetal placentas do not grow together but can be easily separated without tearing; an apposed or contact placenta. (05 Mar 2000) |
| semiplume | <zoology> A feather which has a plumelike web, with the shaft of an ordinary feather. Source: Websters Dictionary (01 Mar 1998) |
| semipolar bond | A bond in which the two electrons shared by a pair of atoms belonged originally to only one of the atoms; often represented by a small arrow pointing toward the electron receiver; e.g., nitric acid, O(OH)N→O; phosphoric acid, (OH)3P→O. Synonym: coordinate covalent bond. (05 Mar 2000) |
| semipronation | The attitude or assumption of a partly prone position, as in Sims' position. (05 Mar 2000) |
| semiprone | Denoting semipronation. (05 Mar 2000) |
| semiprone position | A position to facilitate a vaginal examination, the patient lying on the side with the under arm behind the back, the thighs flexed, the upper one more than the lower. Synonym: English position, lateral recumbent position, semiprone position. (05 Mar 2000) |
| semiquartile | <astronomy> An aspect of the planets when distant from each other the half of a quadrant, or forty-five degrees, or one sign and a half. Source: Websters Dictionary (01 Mar 1998) |
| semiquinone | A free radical resulting from the removal of one hydrogen atom with its electron during the process of dehydrogenation of a hydroquinone to quinone or similar compound (e.g., flavin mononucleotide). (05 Mar 2000) |
| semiquintile | <astronomy> An aspect of the planets when distant from each other half of the quintile, or thirty-six degrees. Source: Websters Dictionary (01 Mar 1998) |
| semirecondite | <zoology> Half hidden or half covered; said of the head of an insect when half covered by the shield of the thorax. Source: Websters Dictionary (01 Mar 1998) |
| semiring | <anatomy> One of the incomplete rings of the upper part of the bronchial tubes of most birds. The semerings form an essential part of the syrinx, or musical organ, of singing birds. Source: Websters Dictionary (01 Mar 1998) |