Definition from Wiktionary, the free dictionary
- длина is a noun, долгий (dolgij) is an adjective. —Stephen (Talk) 18:49, 18 November 2012 (UTC)
- They seem to be genetically related if you go all the way back to Proto-Indo-European.
- длина is from длить, akin to Common Slavonic *dьlgъ (long), but the original PIE etymon of длить is not known.
- долгий (dolgij) is akin to Common Slavonic *dьlgъ (long), Greek δολιχός, Latin indulgeo, and Latin longus, English long, from Proto-Indo-European *dl̥h₁gʰós. —Stephen (Talk) 23:17, 18 November 2012 (UTC)