Змагати : етимологія
ЗМАГА́ТИ «брати гору, перемагати; [спрямовувати, спонукати МСБГ]»
псл. sъmagati «долати», vъzаgati;
пов’язане з *mogti в його первісному значенні «діяти силою, тягти»;
бр. змага́ць «перемагати», п. zmagać, ч. zmáhati «переборювати, осилювати, справлятися з чимось», слц. zmáhať sa «розростатися, міцніти», слн. zmágati «перемагати», стсл. възмагати «тс.»

smags -
Latvian
Etymology
From Proto-Baltic *smag-, from Proto-Indo-European *smog- (“such that it presses heavily; to work hard, to carry a heavy load”). The much broader range of meanings in the Lithuanian cognate was apparently also once present in its Latvian counterpart: remnants are still found in uses like smags gaiss “heavy air” = “stifling,” and, dialectally, also “fast, quick” or “intensely, a lot.” It would seem that the meaning of this word first broadened (“heavy, hard(working)” > “(to hit) heavily, hard” > “strong” > “capable, competent” > “good, nice”) and then was restricted again to “heavy.” (Alternatively, the other uses might result from Lithuanian influence.) Cognates include Lithuanian smagùs (“good, nice, pleasant; joyful, cheerful; fast, quick; strong, agile, skillful; big, intensive; sonorous; rich, well-off; severe, angry, harsh; useful, handy; heavy; stifling”), smōgti (“to hit heavily, strongly; to throw”), Ancient Greek μογέω (mogéō, “I try, strive”), σμογερόν (smogerón, “difficult, painful”)

В свете изложенного имя дракона Смог (Smaug) у Толкина приобретает вполне определённые коннотации. Очевидно, это был дракон-змагарь