The moon tonight is waxing gibbous. “Gibbous” describes the shape of the moon when it is greater than half visible but not quite full. The word "waxing” comes from the Old English word “weaxan”, which meant “to increase". This word also was (and still is) used to describe the process of repeatedly dipping a string into paraffin to make a candle.
The opposite of “waxing” is “waning,” which is a word still in common use today. The etymology of “waning” also goes back to Old English in the form of the word “wan,” which meant “wanting.”
It turns out the word “crescent” also means “to grow” and has its origins in the Latin verb “crescere”, which meant “to grow.” It is interesting that we now use “crescent“ for the shape of the moon whether it is waxing or waning.
Here is another little known fact: if the right side of the moon is lit, it is waxing. If the left side is lit, it is waning.