This word is acceptable for play in the US dictionary that is being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. (physics) A measure of the number of waves in unit distance; inversely proportional to its wavelength

"The use of the term "wavenumber" seems needlessly confusing - you have to define it in terms of the more familiar "wavelength" anyway, so maybe it's worth getting a plot that uses wavelength on the x-axis."

wave vector