col-1

1.
variant of com- before l: collateral.

col-2

1.
variant of colo- before a vowel:
colectomy.
British Dictionary definitions for col-

col-1

prefix
1.
a variant of com- collateral

col-2

prefix
1.
a variant of colo- colectomy

colo-

combining form
1.
indicating the colon: colostomy, colotomy
Word Origin and History for col-

form of Latin com- before stems beginning in -l- (see com-).

col- in Medicine

col- 1
pref.
Variant of com-.

col- 2
pref.
Variant of colo-.