Heard spelling

coreemb

Spelled corymb. two changes at once

Is the middle vowel long?

No. Corymb is said KORR-im, with a short i in the second syllable and the stress on the first.

Coreemb stretches that vowel and shifts the weight of the word onto it. Upsilon is usually read short when a consonant follows, and there are two consonants here even if only one of them is audible.

Say

KORR-im, with the b usually silent

Letters

C-O-R-Y-M-B