Eyetooth \Eye"tooth\ ([imac]"t[=oo]th`), n.; pl. Eyeteeth ([imac]"t[=e]th`) (Anat.) A canine tooth of the upper jaw. See Teeth.

To cut one's eyeteeth, to become acute or knowing. [Colloq.]

Source: Webster's Revised Unabridged Dictionary (1913)