com-prōmitto
mīsi, missum, 3, v. a.
I.
to promise mutually to abide by the decision of an arbiter: tribunicii candidati conpromiserunt, Cic. Q. Fr. 2, 14 (15, 6): de aliquā re, Dig. 4, 8, 13: in arbitrum, ib. 44, 4, 4; 4, 8, 21 al.—
II.
To promise at the same time (very rare): eisque spolia peremptorum hostium compromittens, Cassiod. Hist. Eccl. 6, 1.