1580s, "the action of admitting," formed in English from admit + -ance (if from Latin, it would have been *admittence; French uses accès in this sense). Used formerly in figurative senses where admission now prevails. Admissure was used in this sense from mid-15c.
admirer
admissibility
admissible
admission
admit
admittance
admitted
admix
admixture
admonish
admonition