Kenneth G. Wilson (1923). The Columbia Guide to Standard American English. 1993.
shear (v.)
The principal parts are shear, sheared, sheared. Shorn is frequently the participial adjective, but it can also be the past participle when applied to haircutting or taking honors away: His baby ringlets had been shorn. The senator was shorn of his chairmanship. See also WIND SHEAR.