Synonyms for Capsize:

n.

anchor, bail out, beach, berth, boater, boating, canoe, tip over, turn, Ahoy, the Admiral's Cup, the America's Cup, study at upset. horizontal, knock over, move, overthrow, topple, turn over. capsize (noun)
turn turtle, turtle.

v.

derange (verb)
agitate, blur, botch, churn, clutter, confound, confuse, convulse, derange, disarrange, discompose, dishevel, dislocate, disorder, disorganize, displace, disturb, ferment, hash, jumble, meddle, mess, mislay, misplace, muddle, muss, perturb, ripple, roil, roughen, ruffle, rummage, rumple, scatter, scramble, swirl, tamper, toss, tousle, trouble, tumble, upset, whip, whisk, mix up.
invert (verb)
change, invert, overturn, reverse, transpose, upend, upturn.
motion (verb)
turn turtle, turtle.
overturn (verb)
invert, tip over, turn over, turn turtle, upset.

Other synonyms:

overthrow, topple. flip over
overturn.
invert
upend, upturn.
turn over
turn turtle.
Other relevant words:
knock over, overthrow, tip over, topple, turn, turn over, turn turtle, turtle.

Usage examples for capsize

  1. For an instant it seemed as if the vehicle would capsize under the sudden change of direction. – The Girl Aviators and the Phantom Airship by Margaret Burnham
  2. What were you about to capsize the boat? – The Black Bar by George Manville Fenn
  3. The obligation of the man at the oars was to keep the boat headed so that the tilt of the rollers would not capsize her, and to preserve her from filling when the crests rushed past. – Men, Women, and Boats by Stephen Crane