| overhanging restoration | A restoration with excessive material at the junction of the restoration margin and the tooth. (05 Mar 2000) |
|---|---|
| overhead cover | Material (organic or inorganic) that provides protection to fish or other aquatic animals from above, generally includes material overhanging the stream less than a particular distance above the water surface. Values less than 0.5 m (1.5 feet) and less than 1 m (3 feet) have been used. (09 Oct 1997) |
| overhead projector | <instrument> A projector by which images are reflected by a mirror through a lens, or lenses, onto a screen, using reflected light for opaque objects and transmitted light for translucent or transparent ones. Synonym: overhead projector. Origin: epi-+ G. Dia, through, + skopeo, to view (05 Mar 2000) |
| overhydration | Excess water content of the body; may result from the intravenous administration of unduly large amounts of glucose solution. Synonym: overhydration. (05 Mar 2000) |
| overjet | <dentistry> Horizontal projection of upper teeth beyond the lower. (08 Jan 1998) |
| overlap | 1. The lapping of one thing over another; as, an overlap of six inches; an overlap of a slate on a roof. 2. <geology> An extension of geological beds above and beyond others, as in a conformable series of beds, when the upper beds extend over a wider space than the lower, either in one or in all directions. Source: Websters Dictionary (01 Mar 1998) |
| overlap hybridization | A procedure to find and sequence a gene whose approximate position in a chromosome is known by classical genetic linkage studies. Starting with the known sequence of a gene shown by classical genetics to be near to the novel gene, new clones are picked from a genomic library by hybridisation with a short probe generated from the appropriate end of the known sequence. The new clones are then sequenced, new probes generated and the process repeated until the gene of interest is reached. (18 Nov 1997) |
| overlap index | <cell biology> A measure of the extent to which a population of cells in culture forms multilayers. The predicted amount of overlapping is calculated knowing the cell density, the projected area of the nucleus (usually) and assuming a Poisson distribution. The actual overlap is measured on fixed and stained preparations and the ratio of actual/predicted is derived. A value of 1 implies a random distribution with no constraint on overlapping, normal fibroblasts may have values as low as 0.05. Although a useful measure it does not unambiguously indicate the reason for the effect, which may be contact inhibition of locomotion or differential adhesion of cells between substratum and other cells. (18 Nov 1997) |
| overlapping | <cell biology> In cell locomotion situation in which the leading lamella of one cell moves actively over the dorsal surface of another cell should be distinguished from underlapping. (18 Nov 1997) |
| overlapping gene | <molecular biology> Different genes whose nucleotide coding sequences overlap to some extent. The common nucleotide sequence is read in two or three different reading frames thus specifying different polypeptides. (18 Nov 1997) |
| overlapping reading frame | <molecular biology> Start codons in different reading frames which generate different polypeptides from the same DNA sequence. (09 Oct 1997) |
| overlay | 1. To lay, or spread, something over or across; hence, to cover; to overwhelm; to press excessively upon. "When any country is overlaid by the multitude which live upon it." (Sir W. Raleigh) "As when a cloud his beams doth overlay." (Spenser) "Framed of cedar overlaid with gold." (Milton) "And overlay With this portentous bridge the dark abyss." (Milton) 2. To smother with a close covering, or by lying upon. "This woman's child died in the night; because she overlaid it." (1 Kings III. 19) "A heap of ashes that o'erlays your fire." (Dryden) 3. To put an overlay on. Origin: Overlaid; Overlaying. Source: Websters Dictionary (01 Mar 1998) |
| overlay denture | A complete denture that is supported by both soft tissue and natural teeth that have been altered so as to permit the denture to fit over them. The altered teeth may have been fitted with short or long copings, locking devices, or connecting bars. Synonym: bar joint denture, hybrid prosthesis, overdenture, telescopic denture. (05 Mar 2000) |
| overlearning | Learning in which practice proceeds beyond the point where the act can just be performed with the required degree of excellence. (12 Dec 1998) |
| overlie | To lie over or upon; specifically, to suffocate by lying upon; as, to overlie an infant. "A woman by negligence overlieth her child in her sleeping." (Chaucer) Origin: Overlay; Overlain; Overlying. Source: Websters Dictionary (01 Mar 1998) |