From the Perseus entry for consuesco:<br /><br />consŭesco , suēvi, suētum, 3 (in the tempp. perff. the sync. forms prevail: consuesti, consuestis, consuerunt; consueram, etc.; consuero, etc.; consuerim, etc.; consuessem, etc.; consuesse. Thus also consuēmus = consuevimus, Prop. 1, 7, 5 ), v. a. and n. <br /><br />Could someone refresh my memory as to what sync. forms might be? I vaguely recall something about the -esc- in verbs ending in -esco sometimes dropping out, but I'm very hazy about the details.