The Collaborative International Dictionary
Osculant \Os"cu*lant\, a. [L. osculans, -antis, p. pr. of osculari to kiss. See Osculate.]
Kissing; hence, meeting; clinging.
(Zo["o]l.) Adhering closely; embracing; -- applied to certain creeping animals, as caterpillars.
(Biol.) Intermediate in character, or on the border, between two genera, groups, families, etc., of animals or plants, and partaking somewhat of the characters of each, thus forming a connecting link; interosculant; as, the genera by which two families approximate are called osculant genera.
Wiktionary
a. 1 kiss; hence, touching or meeting; clinging. 2 (context zoology English) adhere closely; applied to certain creeping animals, such as caterpillars. 3 (context biology English) intermediate between two genus, groups, family, etc., and having some of the characteristics of each; interosculant.
Wikipedia
In mathematical invariant theory, the osculant or tacinvariant or tact invariant is an invariant of a hypersurface that vanishes if the hypersurface touches itself, or an invariant of several hypersurfaces that osculate, meaning that they have a common point where they meet to unusually high order.
Usage examples of "osculant".
A few old and intermediate parent-forms having occasionally transmitted to the present day descendants but little modified, will give to us our so-called osculant or aberrant groups.