scrap (n.1)

"small piece," late 14c., from Old Norse skrap "scraps, trifles," from skrapa "to scrape, scratch, cut" (see scrape (v.)). Meaning "remains of metal produced after rolling or casting" is from 1790. Scrap iron first recorded 1794.

scrap (n.2)

"fight," 1846, possibly a variant of scrape (n.1) on the notion of "an abrasive encounter." Weekley and OED suggest obsolete colloquial scrap "scheme, villainy, vile intention" (1670s).

scrap (v.1)

"to make into scrap," 1883 (of old locomotives), from scrap (n.1). Related: Scrapped; scrapping.

scrap (v.2)

"to fight, brawl, box," 1867, colloquial, from scrap (n.2). Related: Scrapped; scrapping.

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Definitions of scrap from WordNet
scrap (n.)
a small fragment of something broken off from the whole;
Synonyms: bit / chip / flake / fleck
scrap (n.)
worthless material that is to be disposed of;
Synonyms: rubbish / trash
scrap (n.)
a small piece of something that is left over after the rest has been used;
she jotted it on a scrap of paper
there was not a scrap left
scrap (n.)
the act of fighting; any contest or struggle;
the unhappy couple got into a terrible scrap
Synonyms: fight / fighting / combat
scrap (v.)
dispose of (something useless or old);
scrap your old computer
Synonyms: trash / junk
scrap (v.)
have a disagreement over something;
These two fellows are always scrapping over something
Synonyms: quarrel / dispute / argufy / altercate
scrap (v.)
make into scrap or refuse;
scrap the old airplane and sell the parts