1540s, type of shrub or tree fund in warm climates of Africa and Australia, from Latin acacia, from Greek akakia "thorny Egyptian tree," a word of uncertain origin. Perhaps it is related to Greek akē "point, thorn" (from PIE root *ak- "be sharp, rise (out) to a point, pierce"), or perhaps it is a Hellenization of some Egyptian word. Beekes suggests it is probably a word from a pre-Greek Mediterranean language and finds "no reason for an Oriental origin." Greek kaktos also has been compared. From late 14c. in English as the name of a type of gum used as an astringent, etc. Extended 17c. to North American trees.
(Latin plural genera), 1550s as a term of logic, "kind or class of things" (biological sense dates from c. 1600), from Latin genus (genitive generis) "race, stock, kind; family, birth, descent, origin" (from suffixed form of PIE root *gene- "give birth, beget," with derivatives referring to procreation and familial and tribal groups).
"cartilaginous fish resembling or related to a shark of the genus selachii," 1835; the genus name from Latinized form of Greek selakhos (plural selakhē) "cartilaginous fish," which is of uncertain origin.
horseshoe crab, king crab, representative genus of the biological family Limulidae, 1837, Modern Latin, from Latin limulus "somewhat askance," diminutive of limus "askance." The genus classification involved the number and position of the eyes.
genus of fungi, Modern Latin, from Greek pilos "felt" (see pileated) + bōlos "a clod, clump."
"Australian duck-mole," 1799, from Modern Latin, from Greek platypous, literally "flat-footed," from platys "broad, flat" (from PIE root *plat- "to spread") + pous "foot," from PIE root *ped- "foot." Originally the genus name, but entomologists had given it earlier to a genus of beetles; it was retained for the species after the genus name was changed in 1800 to Ornithorhyncus. OED has Australian platypussary (1945) "enclosure in which platypuses are kept."