From Proto-Balto-Slavic *kel-, from Proto-Indo-European *kel- (“to lift”) (whence also celt (“to lift, to stand up, to build”)). The semantic evolution went through the fact that old roads through forests and swamps were often build on higher ground (note that notions related to high relief points are often named with derivations from *kel-, like kalns or cēls (“lofty; noble”)). Also, the sense of “start,” “initiate”, or even “lead” found in celt (e.g., celt naidu “to cause hostility,” celt pār upi “to lead over the river”) and neighboring notions may have influenced ceļš (compare the Ancient Greek cognate with its source κελεύω (keleúō, “to urge, to exhort, to command”)). Cognates include Lithuanian kẽlias (“road, way”), Ancient Greek κέλευθος (kéleuthos, “road, path”).
ceļš m (1st declension)