-long,† -longs suffix forming advs.|lɒŋ|The earliest instance is endlong, from ON.endlang-radj., ‘extending from end to end’, ‘the whole length of’. The word is properly a compound of long a.; but in Eng. it was principally used as adv., and developed the sense ‘end-wise’, ‘end foremost’, so that it became parallel in meaning to words like sideling, headling, backling. The ending -long thus came to be regarded as a variant of -ling suffix2. Hence, on the one hand, the occasional 14th c. form endelyng for endlong, and, on the other hand, the substitution of headlong(s, sidelong(s, flatlong(s for the earlier headling(s, sideling(s, flatling(s.
-long
adverbial suffix indicating direction, from Old Norse -langr, from langr "long" (adj.); see long, adj.. Displaced native -ling.
-long/lɒŋ/suffix. Also -longs†.
ORIGIN: from longadjective1.
Forming adverbs and adjectives with the senses ‘-wise’, ‘foremost’, (= -ling2), as headlong, sidelong, and ‘lasting or throughout the specified time’, as daylong, lifelong. (Earliest in endlong.)
-long
Suffix
Forms adjectives indicating duration when suffixed to nouns of duration