In a fleeting, transient, or temporary manner; lasting for only a brief time.
From 'fugacious' (1620s, from Latin 'fugax' meaning 'fleeing'), combined with the -ly adverbial suffix. 'Fugax' comes from 'fugere,' 'to flee,' reflecting the idea of something that runs away or disappears quickly.
The root 'fugere' (to flee) also gives us 'fugitive'—anyone who flees is running away, and anything fugacious is also running away, just in time rather than across borders!
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