Harlequin is the name of the colour that is halfway between green and chartreuse green on the Colour wheel. On color plate 17 in the 1930 book A Dictionary of Colour, the colour harlequin is shown as being on the colour wheel precisely halfway between green and yellow-green (the colour which was formerly called yellow-green is now called chartreuse green). 
The first recorded use of harlequin as a color name in English was in 1923.
↑ Maerz and Paul A Dictionary of Colour New York:1930 McGraw-Hill Colour Sample of Harlequin: Page 57 Plate 17 Colour Sample K11--Harlequin (The colours on the right and bottom of the charts displaying the most saturated colours, of which Plate 17 is one, represent the colours of the Colour wheel.)
↑ Maerz and Paul A Dictionary of Color New York:1930 McGraw-Hill Page 196; Color Sample: Page 57 Plate 17 Color Sample K11--Harlequin