juncture

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The act of joining or the condition of being joined.
• noun A place where two things are joined; a junction or joint.
• noun A point in time, especially one requiring a decision to be made.
• noun The transition or mode of transition from one sound to another in speech.

from The Century Dictionary.

• noun In geometry, either the instantaneous union of a collection of objects which are just moving in coincidence of place, thereafter to be for some lapse of time one object, or the instantaneous loss of one or more dimensions by the gradual shrinkage of a body, this smaller dimensionality lasting through a period of time.
• noun A joining; junction.
• noun The line or point at which two bodies are joined; a joint or articulation; a seam.
• noun A point of time; particularly, a time rendered critical or important by a concurrence of circumstances; a conjuncture.

from the GNU version of the Collaborative International Dictionary of English.

• noun obsolete A joining; a union; an alliance.
• noun The line or point at which two bodies are joined; a joint; an articulation; a seam.
• noun A point of time; esp., one made critical or important by a concurrence of circumstances; hence, a crisis; an exigency.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a place where things join, a junction
• noun a critical moment in time

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a crisis situation or point in time when a critical decision must be made
• noun the shape or manner in which things come together and a connection is made
• noun an event that occurs at a critical time