Grayish-green is a relatively uncommon colour that is a blend of green and grey tones. Its rareness makes it difficult to describe using a single word, but there are some synonyms that can be used to convey its complexity. One option is 'Sage', which is a muted green-grey tone resembling the leaves of a sage plant. Another synonym is 'Seafoam', which is a pale green with a hint of blue mixed with grey. 'Olive' is also a great option as it reflects the dull greenish-grey colour of unripe olives. Lastly, 'Moss' is a dark green with a grey undertone, resembling the hue of Moss.