Dictionary.com
Thesaurus.com

Gram-variable

American  
[gram-vair-ee-uh-buhl] / ˈgræmˈvɛər i ə bəl /

adjective

(often lowercase)
  1. of or relating to bacteria that stain irregularly with Gram's stain, being neither Gram-positive nor Gram-negative.


Etymology

Origin of Gram-variable

First recorded in 1955–60; Gram's method