Partial assimilation vs. total assimilation
An assimilation is total assimilation if the assimilated sound adopts all the phonetic features of another sound and becomes identical to it (e.g. Latin septem 'seven' > Italian sette). An assimilation is partial if the assimilated sound retains at least one of its original phonetic features and adopts only some of the phonetic features of another sound. (Thus, Old English efn 'even' > West-Saxon emn.)