This is the 961st most frequent Hindi word.
ak
"Ak" in Hindi refers to the Calotropis plant, also known as swallow-wort or milkweed.
Here, 'आँख' means 'eye' in the literal sense.
उसने आँख मूंद ली।
He/she closed the eye.
In this usage, 'आँख' metaphorically refers to sight or awareness.
इस परेशानी का समाधान आँख के सामने है।
The solution to this issue is just in front of the eyes.
Here, 'आँख का तारा' is an idiomatic expression meaning someone beloved or cherished.