Dictionary.net

• rim'[=u]-la, n. (conch.) a genus of fossil keyhole limpets.--adjs. RIM'[=U]LIFORM, shaped like a crack; RIM'[=U]LOSE. [L., dim. of rima, a crack.]

1908 - Chambers's Twentieth Century Dictionary of the English Language
By Thomas Davidson

• A minute fissure of the cord or brain.

1898 - American pocket medical dictionary
By Willam Alexander Newman Dorland