Gram-variable

[ gram-vair-ee-uh-buh l ]
/ ˈgræmˈvɛər i ə bəl /

adjective (often lowercase)

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

Origin of Gram-variable

First recorded in 1955–60; see origin at Gram's method