in·cus 
(ĭngkəs)
(ĭngkəs)n. pl. in·cu·des (ĭng-kydēz)
1. An anvil-shaped bone between the malleus and the stapes in the mammalian middle ear. Also called anvil.
2. A thunderhead.
[Latin incūs, incūd-, anvil, from incūsus, past participle of incūdere, to forge with a hammer : in-, intensive pref.; see IN-2 + cūdere, to beat, forge; see kau- in the Appendix of Indo-European roots.]