Learn how to say Achromatic correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word achromatic:
1relating to, using, or denoting lenses that transmit light without separating it into constituent colours:
a lens of achromatic construction
2 literary without colour:
the achromatic gloom
late 18th century: via French from Greek a- ‘without’ + khrōmatikos (from khrōma ‘colour’)