1) The act of coupling 
• (n.) The act of coupling, or the state of being coupled; union. • (n.) That which couples, as a tie or brace.
Ac·cou'ple·ment (-kŭp''l*m e nt) noun [ Confer French accouplement .] 1. The act of coupling, or the state of being coupled; union. [ R.] Caxton. 2. That which couples, as a tie or brace. [ R.]
In architecture, accouplement refers to the placing of columns or pilasters close together in pairs.
the act of coupling. · something that couples, esp. a tie or brace in building.