sosh UK /səʊʃ/US /soʊʃ/ noun4 •(slang) A social security number.He handed her a paper with Erik Last's DOB and Visa card number. "This guy wouldn't give me his sosh." His social security number. — 2003 •(slang) Social studies. •(slang) Abbreviation of various terms beginning "social"; used especially in compound terms.This, more than anything else, was the true sign of a high school social climber known as the “sosh.” The teeth-baring sosh (long o) began as a glimmer in the eye. — 1981 •(Scotland, slang) A co-op.Maggie, rin you to the sosh for a peck o' saut. — 1897 formssoshes