Origin: 1640–50; appar. repr. earlier agar, ager, obscurely akin to hyger, higre; (cf. AL (12th century) higra the tidal bore of the Severn); compared with OE ēgor, eogor flood, high tide, though preservation of g in modern forms is problematic
bore 3 (bôr, bōr) n. A high, often dangerous wave caused by the surge of a flood tide upstream in a narrowing estuary or by colliding tidal currents. Also called eagre.
[Middle English bare, wave, from Old Norse bāra; see bher-1 in Indo-European roots.]