obsolete resistance to drug true OBSOLETE. An increased chemical resistance phenotype observed in the vegetative growth phase of the life cycle in which cells grow in the presence of a higher concentration of a drug than normal. FYPO:0000074 This term was made obsolete because 'drug' is not defined clearly. Search for a specific term for resistance to the substance used in the assay. drug resistance resistant to drugs 2011-03-29T05:53:56Z drug resistant resistance to drug during vegetative growth midori