constrain (v.) Look up constrain at Dictionary.com
early 14c., constreyen, from stem of Old French constreindre (Modern French contraindre) "restrain, control," from Latin constringere "to bind together, tie tightly, fetter, shackle, chain," from com "with, together" (see com-) + stringere "to draw tight" (see strain (v.)). Related: Constrained; constraining.