Word for the shortening of a longer word [eg, polio, burger, auto]

Is there a word for the linguistic tendency to shorten a long word, in which the shorter word also becomes part of the language, the words in the subject shortened from poliomyelitis, hamburger, and automobile, respectively.

‘Elision’ is close, but I dont know if that covers it.

Clipping?

Truncation.

Thanks!