Green’s Dictionary of Slang

1. (US) an aggressive, powerful creature.

1832

Spirit of the Times (NY) 31 Mar. 2/3: [of a fish] He was a ‘tewarer,’ and the best ’un I ever had taken.

2. in prizefighting, a hard blow.

1845

Bell’s Life in Sydney 6 Dec. 4/1: To plant a tearer as the lightning fleet, / Baffle your foe, and mill on the retreat.

3. see tearcat under tear v.