Heard spelling

corim

Spelled corymb. two changes at once

Where did the b go?

Nowhere. It is still on the end of corymb, silently, the way it sits on the end of comb, lamb, thumb and plumb.

English lost the b sound after m several centuries ago and kept the letter. Corymb arrived later, from Latin corymbus, and joined a rule that was already in place. Some speakers do sound the b, which makes the spelling easier to remember and does nothing at all for corim.

Say

KORR-im, with the b usually silent

Letters

C-O-R-Y-M-B