PIE base ‘to push, hit’.
Other derivatives include etude, pierce, steep, steeple, step- (as in stepfather, etc.), stint, stock, stoke, stoop, stub, stucco, study, stupefy, stupid, stutter, timpani, toil, and tweezers.
[Pokorny *(s)teu-1, pp. 1032-1034, with suffixed form D: (s)teu-p.]