ACHROMIC
achromic, achromous
(adjective) having no color
Source: WordNet® 3.1
Adjective
achromic (comparative more achromic, superlative most achromic)
(science) Uncoloured; not pigmented; lacking in colour.
Usage notes
The OED regards this word as obsolete, but modern usage shows a return of this synonym for achromatic in the fields of medicine and chemistry.
Source: Wiktionary
A*chro"mic, a. [Gr. colorless; priv. + color.]
Definition: Free from color; colorless; as, in Physiol. Chem., the achromic
point of a starch solution acted upon by an amylolytic enzyme is the
point at which it fails to give any color with iodine.
Source: Webster’s Unabridged Dictionary 1913 Edition