The Collaborative International Dictionary
Athalamous
Athalamous \A*thal"a*mous\, a. [Gr. 'a priv. + ? nuptial bed.] (Bot.) Not furnished with shields or beds for the spores, as the thallus of certain lichens.
Wiktionary
athalamous
a. (context botany rare English) Not furnished with shields or beds for the spores, like the thallus of certain lichens.