Paleotherium \Pa`le*o*the"ri*um\, n. [NL., fr. Gr. ? ancient + ? beast.] (Paleon.) An extinct genus of herbivorous Tertiary mammals, once supposed to have resembled the tapir in form, but now known to have had a more slender form, with a long neck like that of a llama. [Written also {Pal[ae]otherium}.]