intromission

n.
The act or process of intromitting; introduction or admission.

[Medieval Latin intrōmissiō, intrōmissiōn-, usurpation, from Latin intrōmissus, past participle of intrōmittere, to intromit. See intromit.]

intromissive in'tro·mis'sive (-mĭs'ĭv) adj.

noun

The state of being allowed entry: admission, admittance, entrance¹, ingress, ingression, introduction. See accept/reject.

The entrance of one part or object into another.