Lewis & Short

con-sŏcer, ĕri, m.; -crus, ūs, f.; a designation of the fathers and mothers of a married pair, a joint father-in-law or mother-in-law; one of two fathers-in-law or mothers-in-law; masc., Suet. Claud. 29; Dig. 24, 1, 32, § 20 sq.; Aus. Parent. Mart. 10, 33, 3.
* Fem., Aus. Parent. 30 inscr.