(in several languages) The imperfect tense in the subjunctive mood.
Imperfect-subjunctive Sentence Examples
of the imperfect (canidbamos, canidbais), of the pluperfect indicative (cantdramos, cantdrais), and of the imperfect subjunctive (cantdsemos, cantdseis); possibly the impulse to this was given by the forms of future perfect canidremos, cantdreis (cantarlrnus, caniarilis).
Apparently, you don't use the imperfect subjunctive in day-to-day conversation.
It is made up of the imperfect subjunctive of the auxiliary verbs followed by the past participle.