(1):

(n.) A place which is open; a breach; an aperture; a gap; cleft, or hole.

(2):

(n.) A thinly wooded space, without undergrowth, in the midst of a forest; as, oak openings.

(3):

(n.) Hence: A vacant place; an opportunity; as, an opening for business.

(4):

(n.) The act or process of opening; a beginning; commencement; first appearance; as, the opening of a speech.

(5):

(p. pr. & vb. n.) of Open