Flirting is a playful, romantic or sexual overture by one person to another subtly indicating an interest in a deeper relationship with the other person, and can involve verbal communication as well as body language. Body language can include flicking the hair, eye contact, brief touching, open stances, proximity etc. Verbal communication of interest can include the vocal tone, such as pace, volume, intonation. Challenges (teasing, questions, qualifying, feigned disinterest) serve to increase tension, test intention and congruity.
Flirting usually involves speaking and behaving in a way that suggests a mildly greater intimacy than the actual relationship between the parties would justify, though within the rules of social etiquette, which generally disapproves of a direct expression of sexual interest. This may be accomplished by communicating a sense of playfulness or irony. Double entendres, with one meaning more formally appropriate and another more suggestive, may be used.
Hoyt's New Cyclopedia Of Practical Quotations 
- Quotes reported in Hoyt's New Cyclopedia Of Practical Quotations (1922), p. 277.
- I assisted at the birth of that most significant word flirtation, which dropped from the most beautiful mouth in the world, and which has since received the sanction of our most accurate Laureate in one of his comedies.
- Flirtation, attention without intention.
- Max O'Rell, John Bull and his Island.
- From a grave thinking mouser, she was grown
The gayest flirt that coach'd it round the town.
- William Pitt, Fable, The Young Man and His Cat.
- Ye belles, and ye flirts, and ye pert little things,
Who trip in this frolicsome round,
Pray tell me from whence this impertinence springs,
The sexes at once to confound?
- Paul Whitehead, Song for Ranelagh.