köken: From Old Swedish glaven (glaffwin, glawan) n, m, glavene n, variant of glävia, glafwia, glafwa f, from Middle Low German glave, gleve, glevie, obl. & pl. glaven, from Old French glaive (“lance,”) from Latin gladius (“sword”); possibly of Celtic origin. Compare Danish glavind, Icelandic glefja, English glaive.
The spelling means “long blade”. Compound of 長 (naga, “long”, the stem of adjective 長い (nagai, “long”)) + 刀 (katana, “katana, the traditional single-bladed Japanese sword”). Encountered with both the unvoiced nagakatana and voiced nagagatana readings. The voiced reading may be more common, wherein the katana changes to gatana as an instance of rendaku (連濁).