| primary colour | The three colour's of the retinal cone pigments (red, green, blue) that may be combined to match any hue. Synonym: simple colour. (05 Mar 2000) |
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| primary complex | The typical lesions of primary pulmonary tuberculosis, consisting of a small peripheral focus of infection, with hilar or paratracheal lymph node involvement. (05 Mar 2000) |
| primary constriction | The narrowing between the two arms of the chromosome represented by the centromere. (05 Mar 2000) |
| primary dental lamina | dental ledge |
| primary dentin | Dentin which forms until the root is completed. (05 Mar 2000) |
| primary dentition | The set of 20 first (deciduous) teeth. The primary dentition is as opposed to the secondary (permanent) dentition. at birth, both sets of dentition are evident by X-ray. (12 Dec 1998) |
| primary deviation | The ocular deviation seen in paralysis of an ocular muscle when the nonparalysed eye is used for fixation. (05 Mar 2000) |
| primary digestion | Digestion in the alimentary tract. (05 Mar 2000) |
| primary disease | A disease that arises spontaneously and is not associated with or caused by a previous disease, injury, or event, but which may lead to a secondary disease. (05 Mar 2000) |
| primary dried yeast | A source of dried yeast; obtained from suitable strains of Saccharomyces cerevisiae grown in media other than those required for the production of beer. (05 Mar 2000) |
| primary drives | Those drives such as hunger and thirst which stem from the biological needs of an organism. Synonym: primary drives. (05 Mar 2000) |
| primary dysmenorrhoea | <gynaecology> Painful menses due to a functional disturbance and not due to organic factors such as growths, inflammation or anatomy. (06 Mar 1998) |
| primary egg membrane | See: egg membrane. (05 Mar 2000) |
| primary embryonic cell | In a very young embryo, a cell still capable of differentiation. (05 Mar 2000) |
| primary energy | <radiobiology> Energy before conversion. For instance, the United States uses about 30,000 megajoules of electricity per capita per year, but electricity is generally obtained by converting other forms of energy (primarily chemical/heat) at an efficiency of around 30%, so the U.S. Consumes 90,000 megajoules of primary energy per capita for electrical use. (Total U.S. Primary energy consumption is 300,000 megajoules per capita.) (09 Oct 1997) |