What is the Meaning of a Wink--USA and Elsewhere?

From OZ:

A winker winks at a winkee to send a soundless message of co-conspiracy, without a third party or parties knowing.

Particularly useful if you are stirring a third party up (ie pulling his/her leg) and want the winkee to know that is what you are doing or to signal you are doing something out of the ordinary. This sort of banter is pretty common in Oz social interactions.

An exaggerated wink is sometimes used to signal agreement/approval, sort of an equivalent to a 'thumbs up' gesture.

Any man who used winking as some way to entice a female would be politely asked if he had something in his eye.

I'd say I have seen it used the same way here. I've given my niece a wink when I was trying to indicate to her that either I or someone else was joking with her.

One alternative usage for me is between a couple pair at a crowded event. One is talking to someone across the room and the other notices s/he is looking nervous/bored/tired - a quick wink to indicate that you notice what that person is feeling.

To give s.o. a wink (in German: "jemandem einen Wink geben"), means to give s.o. a hint. (Can be a broad one, with a 'fence post'.)

This expression derives from the nautical language/semaphor use.

I grew up in Munich and we call it "zwinkern"
and for us it meant indicating something 2 people share:
a joke, a hint, or sometimes in a flirtatious manner,
while holding eye contact.

It can definitely be used as flirting. Context -- a group of people are chatting or doing something that doesn't entail much eye contact. Person A becomes aware that person B is looking at him/ her. While person A is noting this, person B holds the gaze for a moment, then winks followed by a smile.

I wink at my daughter all the time. Usually it's when she's doing something on her own, I'm doing something on my own and want to continue, and she glances at me. It's vaguely "hi there sweetie, how's it going?" If she's fine, she winks back -- if she wants more attention, she comes and climbs on me at that point.

The meaning of a wink in the US depends on circumstances. It can be flirtatious, as a wink to say I like your looks. It can be a silent way of expressing agreement or sympathy; or a way of saying, "I'm pulling your leg!"

Wow I had not a clue

RIP Noddy.