Nîn?? In my dictionary it has nîn with three meanings. Nîn I means "my", nîn II means "tear" (I assume tear of your eye rather than tear something apart), and nîn III means wet and watery. I was gonna ask how do you keep from getting confused when you see it but I suppose you know which one it is by its relationship with the word it's used with, such as "Haudh nîn" (watery grave) or "Naer nîn" (A sad tear) or "I eneth nîn (My name is...) .. Sindarin is so fascinating. If only Tolkien had lived long enough to complete it and all its parts, grammar, more vocabulary, etc.
What do I know of cultured ways, the gilt, the craft and the lie?
I, who was born in a naked land and bred in the open sky.
The subtle tongue, the sophist guile, they fail when the broadswords sing;
Rush in and die dogs--I was a man before I was a king!
---From The Road of Kings
I like to think of that (and Lim - swift, Lim - clear, Lim - large fish) as the Sindarin equivalents of the English 'to, too and two' or 'there, their and they're'. We know the differences between these based on context, and the Elves would be able to do the same with these
For nîn, the one that means 'my' isn't an issue, for example: I degil nîn = My pen If you write Tegil nîn it has to mean either 'A sad pen' or 'A watery pen', and just from that short sentence you can't tell which! But like I say, context from the rest of the conversation would give you the answer.