olˈigarchy /-är-ki/ noun

1. Government by a small exclusive class
2. A state so governed
3. A small body of people who have the supreme power of a state in their hands

oligist /olˈi-jist/ noun (Fr fer oligiste, from fer iron, and Gr oligistos, superlative of oligos little; as containing less iron than magnetite; mineralogy)

Crystallized haematite

Oligocene /olˈi-gə-sēn/ adjective (Gr kainos new; as having few fossil molluscs of living species; geology)

Of or belonging to an epoch of the Tertiary period, between 34 and 23 million years ago (also noun)

oligochaete /olˈi-gə-kēt/ noun

(Gr chaitē bristle) any worm of the Oligochaeˈta, chaetopods in which the locomotor organs are reduced to bristles, eg earthworms, etc

oligochrome /olˈi-gə-krōm/ adjective

(Gr chrōma colour) painted in few colours (also noun)

oligoclase /olˈi-gə-klās or -klāz/ noun (Gr klāsis cleavage, because thought to have a less perfect cleavage than albite; mineralogy)

A soda-lime triclinic feldspar

oligocythaemia /ol-i-gō-sī-thēˈmi-ə/ noun

(Gr kytos a vessel, and haima blood) a deficiency of red cells in the blood

oligˈomer noun

A polymer made up of two, three or four monomer units

oligomˈerous adjective

1. (Gr meros a part) having few parts
2. Having fewer members than the other whorls of a flower

oligonūˈcleotide noun

A nucleic acid with few nucleotides

oligopepˈtide noun

A peptide composed of no more than ten amino acids

oligopˈolist noun

oligopolistˈic adjective

oligopoly /ol-i-gopˈə-li/ noun

(Gr pōleein to sell) a situation in which there are few sellers of a particular product or service, and a small number of competitive firms control the market

oligopsonistˈic adjective

oligopsony /ol-i-gopˈsə-ni/ noun

(Gr opsōnia purchase of food) a situation in which a few large buyers purchase all or most of the output of a particular industry, each competitive buyer influencing the market

oligosaccharide /-sakˈə-rīd/ noun

A complex sugar containing between two and ten monosaccharide units linked together

oligospermˈia noun

The condition of having an abnormally low number of sperm cells in the semen, a major cause of male infertility

oligotrophic /-trofˈ/ adjective

(Gr trophē nourishment) (of a lake) having steep, rocky shores and scanty littoral vegetation, lacking in nutrients but rich in oxygen at all levels

oligotˈrophy noun

oliguria /o-li-gūˈri-ə/ noun (Gr ouron urine; medicine)

Scantiness of urine secretion in proportion to liquid intake

oliguˈric adjective