acr/acu

sharp; bitter

Spelled acr, acu, acerb · acer 'sharp, pungent', acuere 'sharpen', and related acerbus 'bitter, harsh'

Latin acer meant 'sharp': acrid smoke bites the nose, acerbity sharpens a remark, and acumen gives the mind an edge.

Words built from it

acute — sharp, intense, or keenly perceptive
acu (sharpen)
acrid — having a strong, unpleasant smell or taste
acr (pungent) + -id (having the quality of)
acrimony — bitterness or harshness in speech or feeling
acr (bitter) + -mony (quality)
acerbity — sharp bitterness in manner, speech, or taste
acerb (bitter) + -ity (quality)
exacerbate — make a problem or unpleasant condition worse
ex- (intensively) + acerb (bitter) + -ate (make)
acumen — the ability to understand situations and make good judgments
acu (sharpen) + -men (result)
acuity — sharpness of perception or thought
acu (sharp) + -ity (quality)

acrobat — From Greek akros (high, at the top) + bates (walker). It uses a different acr-, not Latin acer or acuere.