† ˈbrainletObs. [f. brain n. + -let, transl. L. cerebellum ‘little brain’.] The cerebellum. 1668Culpepper & Cole Barthol. Anat. iii. ii. 130 The Cerebellum, Brainlet, or petty-brain.a1720Gibson Farrier's Guide i. iv. (1738) 35 Cerebellum, or Brainlet.