Elongated form of すごい.

(mathematics) quod erat demonstrandum (that which was to be proved)

(Internet slang) a dead fad; out of fashion; no longer trendy

a lethal technique / a fighter's finishing move, ultimate technique, or coup de grâce, often in contexts such as pro wrestling or video games

An underhanded trick. / A lifehack.

(judo) yuko, points or the judge call to the points in judo match. Fewer points to ippon.

(fiction) name of a technique / move

everything

(colloquial) current boyfriend

(slang) Alternative form of 彼氏 (kareshi, “boyfriend”)