Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
DISSIMILATION
is a process in speech whereby one of two similar sounds gets changed or dropped as we actually say the word in context. In English, l’s and r’s are the sounds most often affected: thermometer gets pronounced thuh-MAHM-i-tuhr, governor GUHV-uh-nuhr, and colonel KUHR-nuhl. The first two examples are acceptable at all levels except the Oratorical; colonel is pronounced in the dissimilated fashion at all Standard English levels.
