| heteroclite | Deviating from ordinary forms or rules; irregular; anomalous; abnormal. Origin: L. Heteroclitus, Gr.; other + to lean, incline, inflect: cf. F. Heteroclite. 1. A word which is irregular or anomalous either in declension or conjugation, or which deviates from ordinary forms of inflection in words of a like kind; especially, a noun which is irregular in declension. 2. Any thing or person deviating from the common rule, or from common forms. Source: Websters Dictionary (01 Mar 1998) |
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| heteroclitical | Deviating from ordinary forms or rules; irregular; anomalous; abnormal. See: Heteroclite. Source: Websters Dictionary (01 Mar 1998) |
| heterocrine | Denoting the secretion of two or more kinds of material. Origin: hetero-+ G. Krino, to separate (05 Mar 2000) |
| heterocrisis | Rarely used term for an irregular crisis, one occurring at an abnormal time or with unusual symptoms. (05 Mar 2000) |
| heterocyclic compound | Any compound in which the constituent atoms, or any part of them, form a ring. Used mainly in organic chemistry where: 1) numerous compound's contain rings of carbon atoms (carbocyclic compound's) or carbon atoms plus one or more atoms of other types (heterocyclic compound's), usually nitrogen, oxygen, or sulfur; 2) where the atoms in the ring are all of the same element (homocyclic or isocyclic compound); 3) where the ring is saturated or contains nonconjugated double bonds (alicyclic compound), the compound is similar in properties to the corresponding acyclic compound (e.g., cyclohexane resembles hexane); 4) where the ring contains conjugated double bonds in a closed loop in which there are 4n + 2 (where n is an integer) delocalised π electrons (Huckel's rule) (aromatic compound; e.g., benzene, pyridine), it is more stable than the corresponding saturated ring and exhibits unusual chemical properties characteristic of itself and not of other types of rings or of acyclic compound's. These aromatic compounds have the ability to sustain an induced ring current. Synonym: closed chain compound, ring compound. (05 Mar 2000) |
| heterocyclic compounds | Ring compounds having atoms other than carbon in their nuclei. (12 Dec 1998) |
| heterocyclic compounds with 4 or more rings | A class of organic compounds containing four or more ring structures, one of which is made up of more than one kind of atom, usually carbon plus another atom. The heterocycle may be either aromatic or nonaromatic. (12 Dec 1998) |
| heterocyclic compounds, 1-ring | A class of organic compounds containing a ring structure made up of more than one kind of atom, usually carbon plus another atom. The ring structure can be aromatic or nonaromatic. (12 Dec 1998) |
| heterocyclic compounds, 2-ring | A class of organic compounds containing two ring structures, one of which is made up of more than one kind of atom, usually carbon plus another atom. The heterocycle may be either aromatic or nonaromatic. (12 Dec 1998) |
| heterocyclic compounds, 3-ring | A class of organic compounds containing three ring structures, one of which is made up of more than one kind of atom, usually carbon plus another atom. The heterocycle may be either aromatic or nonaromatic (12 Dec 1998) |
| heterocyclic compounds, bridged-ring | A class of organic compounds which contain two rings that share a pair of bridgehead carbon atoms. (12 Dec 1998) |
| heterocyclic oxides | Oxides of a ring compound having atoms other than carbon in its ring. (12 Dec 1998) |
| heterocyst | <biology> Specialised cell type found at regular intervals along the filaments of certain Cyanobacteria, site of nitrogen fixation. (18 Nov 1997) |
| heterocytotropic | Having an affinity for cells of a different species. Origin: hetero-+ G. Kytos, cell, + trope, a turning toward (05 Mar 2000) |
| heterocytotropic antibody | A cytotropic antibody (chiefly of the IgG class) similar in activity to homocytotropic antibody, but having an affinity for cells of a different species rather than for cells of the same or a closely related species. (05 Mar 2000) |