1580s, "slight skin tear produced by a sharp thing," from scratch (v.). Meaning "mark or slight furrow in metal, etc." is from 1660s. American English slang sense of "money" is from 1914, of uncertain signification. Many figurative senses (such as up to scratch, originally "ready to meet one's opponent") are from sporting use for "line or mark drawn as a starting place," attested from 1778 (but the earliest use is figurative); meaning "nothing" (as in from scratch) is 1918, generalized from specific 19c. sporting sense of "starting point of a competitor who receives no odds in a handicap match." Sense in billiards is from 1850. Scratch-pad is attested from 1883.
"tear in pieces, strike asunder," c. 1200, from a Scandinavian or North Sea Germanic source akin to Old Norse rifa "to tear apart," from Proto-Germanic *rifanan "to tear, scratch" (compare Swedish rifva, Danish rive "scratch, tear"), from PIE root *rei- "to scratch, tear, cut" (see riparian).
phylum of stinging invertebrates, 1860, with abstract noun ending -ia + Latinized form of Greek knidē "nettle," from stem of knizein "to scratch scrape," which is of uncertain origin. Beekes compares Lithuanian knìsti "to scratch, itch, tickle," knisù "to grub up;" Latvian knidet "to itch, geminate, creep;" Old Norse hnita "to push against;" Middle Irish cned "wound." Related: Cnidarian.
Old English writan "to score, outline, draw the figure of," later "to set down in writing" (class I strong verb; past tense wrat, past participle writen), from Proto-Germanic *writan "tear, scratch" (source also of Old Frisian writa "to write," Old Saxon writan "to tear, scratch, write," Old Norse rita "write, scratch, outline," Old High German rizan "to write, scratch, tear," German reißen "to tear, pull, tug, sketch, draw, design"), outside connections doubtful.
For men use to write an evill turne in marble stone, but a good turne in the dust. [More, 1513]
Words for "write" in most Indo-European languages originally mean "carve, scratch, cut" (such as Latin scribere, Greek graphein, glyphein, Sanskrit rikh-); a few originally meant "paint" (Gothic meljan, Old Church Slavonic pisati, and most of the modern Slavic cognates). To write (something) off (1680s) originally was from accounting; figurative sense is recorded from 1889. Write-in "unlisted candidate" is recorded from 1932.