A primitive root; to fold together; figuratively, to repeat -- double.
H3717. kaphal
כָּפַל verb double, double over (late) (Late Hebrew id.; Aramaic כְּפַל; ᵑ7. כּוּפְלָה כִּיפְלָא,, Nabataean כפל EutNab. No. 20, 7 the double; Christian-Palestinian Aramaic SchwIdioticon 46; North Syriac id.; Arabic the double, posteriors, buttocks; Ethiopic is divide, a part) —
Qal Perfect2masculine singular וְכָפַלְתָּ֫ Exodus 26:9 and thou shalt double over the sixth curtain, i.e. probably use it double (Di); Passive participle כָּפוּל folded double, of the breastpiece (חשֶׁןׅ 28:16; 39:9 (twice in verse).
Niph`al Imperfect3feminine singular וְתִכָּפֵל Ezekiel 21:19 and let the sword be doubled, but very dubious; Co reads plausibly תְּשַׁכֵּל let the sword bereave (compare VB).