'quickly-gained' is a compound adjective formed from the adverb 'quickly' and the past participle 'gained.' 'Quickly' comes from Old English 'cwiclice' meaning 'lively, rapidly,' and 'gained' is the past participle of 'gain,' which comes from Old French 'gaaignier' meaning 'to earn, win.'

'quickly-gained' is a modern English compound, formed by combining 'quickly' and 'gained' to describe something obtained rapidly. The use of hyphenated adjectives is a common feature in modern English.

Initially, the words 'quickly' and 'gained' had their own meanings, but as a compound, 'quickly-gained' specifically refers to something acquired in a short time.