1825 (n.), "mush," a variant of mush. As a verb, by 1980. Compare mash/smash.
Entries linking to smush
mush n.
"kind of porridge; meal boiled in water or milk until it forms a thick, soft mass," 1670s, in the American colonies, a variant of mash (n.) "soft mixture." Meaning "anything soft and thick" is attested from 1824.
mash n.
"soft mixture, mass of ingredients beaten or stirred together," late Old English *masc (in masc-wyrt "mash-wort, infused malt"), from Proto-Germanic *maisk- (source also of Swedish mäsk "grains for pigs," German Maisch "crushed grapes, infused malt," Old English meox "dung, filth"), possibly from PIE root *meik- "to mix."
Originally a word in brewing; general sense of "anything reduced to a soft pulpy consistency" is recorded from 1590s, as is the figurative sense "confused mixture, muddle." Short for mashed potatoes it is attested from 1904.
smash v.
1759, transitive, "break to pieces," earlier "kick downstairs" (c. 1700), probably of imitative origin (compare smack (v.), mash (v.), crush (v.)). The intransitive meaning "act with crushing force" is from 1813; the transitive sense of "strike violently" is from 1835. Tennis sense is from 1882. Smash-and-grab (adj.) as a type of burglary or robbery is attested from 1927.