pertaining to a proposed meta-family of languages including Indo-European, Semitic, Altaic, and Dravidian, 1966 (Nostratian is from 1931), from Latin nostratis "of our country," from nostras "our countrymen," plural of nostrum, neuter of noster "our," from nos "we" (from PIE *nes- (2); see us).
c. 1600, "a medicine made of secret ingredients by secret methods," but commonly "quack medicine," from Latin nostrum remedium "our remedy" (or some similar phrase), presumably indicating "prepared by the person offering it," from Latin nostrum, neuter of noster "our," from nos "we," from PIE *nes- (2); see us. In extended use, "a pet scheme for accomplishing something" (1749).
Old English toð (plural teð), from Proto-Germanic *tanthu- (source also of Old Saxon, Danish, Swedish, Dutch tand, Old Norse tönn, Old Frisian toth, Old High German zand, German Zahn, Gothic tunþus), from PIE root *dent- "tooth." Plural teeth is an instance of i-mutation.
The loss of -n- before spirants is regular in Old English, Old Frisian, and Old Saxon: compare goose (n.), five, mouth (n.). Also thought, from stem of think; couth from the stem of can (v.1); us from *uns.
Application to tooth-like parts of other objects (saws, combs, etc.) first recorded 1520s. Tooth and nail as weapons is from 1530s. The tooth-fairy is attested from 1964.
Old English ure "of us, pertaining to or belonging to us," genitive plural of the first person pronoun, from Proto-Germanic *ons (source also of Old Saxon usa, Old Frisian use, Old High German unsar, German unser, Gothic unsar "our"), from PIE *nes-, oblique case of personal pronoun in first person plural (source of Latin nos "we," noster "our"). Also compare ours.
Ourselves (late 15c.) "we or us, not others," modeled on yourselves, replaced original construction we selfe, us selfum, etc. It often is added to we for emphasis.
