Note that some dictionaries list "busses" as an acceptable plural for "bus." Presumably, this is because the plural "buses" looks like it ought to rhyme with the plural of "fuse," which is "fuses." "Buses" is still listed as the preferable plural form. "Busses" is the plural, of course, for "buss," a seldom used word for "kiss."
There are several nouns that have irregular plural forms. Plurals formed in this way are sometimes called mutated (or mutating) plurals.…
