"notched on the edge like a saw," 1660s, from Latin serratus "sawlike, notched like a saw," from serra "a saw" (also a name of a type of serrated battle formation), a word of unknown origin. De Vaan suggests a connection to Latin sario 'to hoe, weed," and a PIE source in *sers- "cutting off." Related: Serrated; serrating.
1776, "irregularly saw-toothed," from Modern Latin runcinatus, from Latin runcina "a (carpenter's) plane."
"condition of being serrated, formation in the shape of the edge of a saw," 1808, noun of state from serrate (v.), for which see serrate (adj.).
"miner's pick," 1510s, of unknown origin; perhaps borrowed from French mandrin, itself of unknown origin. Also applied from 17c. to a bar or spindle, used chiefly to hold articles in place, on a lathe or a circular saw.
1843, "to seesaw," alteration of Middle English titter "move unsteadily," probably from a Scandinavian source akin to Old Norse titra "to shake, shiver, totter, tremble," from Proto-Germanic *ti-tra- (source also of German zittern "to tremble"). Meaning "move unsteadily, be on the edge of imbalance" is from 1844.
Noun teeter-totter "see-saw" is attested from 1871 (earlier simply teeter, 1855, and titter-totter in same sense is from 1520s). Totter (n.) "board swing" is recorded from late 14c.; see totter (v.), and compare see-saw.
1560s, in geometry, "a solid whose bases or ends are any similar, equal, and parallel plane polygons, and whose sides are parallelograms" (not always triangular), from Late Latin prisma, from Greek prisma "a geometrical prism, trilateral column," (Euclid), literally "something sawed (as a block of wood), sawdust," from prizein, priein "to saw" (related to prion "a saw"), which is of uncertain origin. Euclid chose the word, apparently, on the image of a column with the sides sawn off.
Specific sense in optics, "an instrument (usually triangular) with well-polished sides of glass, quartz, etc., which refracts light and spreads it in a spectrum," is attested from 1610s.