Old English brecan "to break, shatter, burst; injure, violate, destroy, curtail; break into, rush into; burst forth, spring out; subdue, tame" (class IV strong verb; past tense bræc, past participle brocen), from Proto-Germanic *brekan (cf. Old Frisian breka, Dutch breken, Old High German brehhan, German brechen, Gothic brikan), from PIE root *bhreg- "to break" (see fraction). Most modern senses were in Old English. In reference to the heart from early 13c. Meaning "to disclose" is from early 13c.
Break bread "share food" (with) is from late 14c. Break the ice is c.1600, in reference to the "coldness" of encounters of strangers. Break wind first attested 1550s. To break (something) out (1890s) probably is an image from dock work, of freeing cargo before unloading it. Ironic theatrical good luck formula break a leg has parallels in German Hals- und Beinbruch "break your neck and leg," and Italian in bocca al lupo. Evidence of a highly superstitious craft (cf. Macbeth).