"large nail," mid-14c., perhaps from or related to a Scandinavian word, such as Old Norse spik "splinter," Middle Swedish spijk "nail," from Proto-Germanic *spikaz (source also of Middle Dutch spicher, Dutch spijker "nail," Old English spicing "large nail," Old English spaca, Old High German speihha "spoke"), from PIE root *spei- "sharp point" (source also of Latin spica "ear of corn," spina "thorn, prickle, backbone," and perhaps pinna "pin" (see pin (n.)); Greek spilas "rock, cliff;" Lettish spile "wooden fork;" Lithuanian speigliai "thorns," spitna "tongue of a buckle," Old English spitu "spit").

The English word also might be influenced by and partly a borrowing of Latin spica (see spike (n.2)), from the same root. Slang meaning "needle" is from 1923. Meaning "pointed stud in athletic shoes" is from 1832. Electrical sense of "pulse of short duration" is from 1935.

c. 1300, "cinch on a nail;" c. 1400, "short metal pin or bolt inserted through a hole at the junction of two or more metal pieces," the point then hammered broad to hold them together; from Old French rivet "nail, rivet," from river "to clench, fix, fasten," which is of uncertain origin; possibly from Middle Dutch wriven "turn, grind," and thus related to rive (v.). Or the English word might be directly from Middle Dutch.

Proto-Indo-European root meaning "tooth, nail." 

It forms all or part of: cam (n.1) "projecting part of a rotating machinery;" comb; gem; oakum; unkempt.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit jambha-s "tooth;" Greek gomphos "peg, bolt, nail; a molar tooth;" Albanian dhemb "tooth;" Old English camb "comb." 

c. 1600, from thumb (n.) + nail (n.). Meaning "drawing or sketch of a small size" (though usually not literally the size of a thumbnail) is from 1852.

"workshop where nails are made," 1798, from nail (n.) + -ery or from nailer "one who makes nails" (mid-15c.) + -y (1).

late 14c., "to attach" with a nail, etc., from tack (n.1). Meaning "to attach as a supplement" (with suggestion of hasty or arbitrary proceeding) is from 1680s. Related: Tacked; tacking.

"hoofed," 1802, from Late Latin ungulatus "hoofed," from ungula "hoof, claw, talon," diminutive (in form but not sense) of unguis "nail" (see ungual). Ungulata, the order of hoofed mammals, is recorded from 1839.

1570s, from French équipage (15c.), from équiper "to fit out" (see equip). Now largely replaced by equipment. In 18c. often especially tweezers, a toothpick, earpick, nail-cleaner, etc., carried on the person in a small case.

variety of common cabbage with a dense, edible head, 1690s, from Italian broccoli, plural of broccolo "a sprout, cabbage sprout," diminutive of brocco "shoot, protruding tooth, small nail," from Latin broccus (see broach (n.)).

"covered with down; resembling down," 1570s, from down (n.1) + -y (2). Related: Downiness.