Rashi on Leviticus 8:22/רש"י על ויקרא ח׳:כ״ב

1איל המלאים — This means the same as איל השלמים, for the word מלואים is synonymous with the word שלמים; this term is used to describe the ram because by means of it they set the priest fully (ממלאין) and completely (משלימין) in their priestly office (cf. Sifra, Tzav, Mechilta d'Miluim 1 20).