Extended Strong's Greek Lexicon (Abbott-Smith based)
to stumble
Usage: πταίω [in LXX chiefly for נָגַף ni. ;] __1. trans., to cause to stumble (1Ki.4:3, cf. Deiss., BS, 681). __2. Intrans., to stumble. Metaphorical, in moral sense, Rom.11:11, Jas.2:10 3:2, 2Pe.1:10.† (AS)