memory alpha
Multiple realities
(covers information from several alternate timelines)

The action of a flirt was a playful and lighthearted way of expressing romantic or sexual interest in someone.

(ENT: "Shockwave")

In 2259 of the alternate reality, upon hearing Leonard McCoy's attempts to woo Carol Marcus on a planetoid where they were to examine an advanced long-range torpedo, James T. Kirk reminded the doctor that he was not there to flirt. (Star Trek Into Darkness)

(Star Trek IV: The Voyage Home)

In 2366, Youngblood was having a drink with Ensigns Darien Wallace and Bennett in Ten Forward when he was made aware by Bennett that a woman was looking at him. This was watched by Guinan and Lal; the El-Aurian explained to the android that this was called flirting. (TNG: "The Offspring")

(DS9: "The Ascent")

(VOY: "Real Life")

(DS9: "Afterimage")

(VOY: "The Killing Game, Part II")

(VOY: "Gravity")

(VOY: "Workforce, Part II")

(PIC: "The Star Gazer")

(PIC: "Dominion")

(LD: "Parth Ferengi's Heart Place")

(DIS: "Lagrange Point")

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