-ulum

Etymology 1
A phonologically conditioned alteration (allomorph) of Latin, from , generated by a rule deleting the suffix-initial stop in positions after stops.

Suffix

 * < *spek-klo- < *spek-tlo-
 * < *vink-klo- < *vink-tlo-
 * < *spek-klo- < *spek-tlo-
 * < *vink-klo- < *vink-tlo-

Etymology 2
Inflected from.