mid 16th cent.: apparently symbolic, the elements fl- and -irt both suggesting sudden movement; compare with flick and spurt. The original verb senses were give someone a sharp blow and 'sneer at'; the earliest noun senses were 'joke, gibe' and 'flighty girl' (defined by Dr Johnson as a 'pert young hussey'), with a notion originally of cheeky behaviour, later of playfully amorous behaviour
