As commonly explained, abstain from everything that even looks like evil. But the word signifies form or kind. Comp. Luk 3:22; Joh 5:37, and see nearly the same phrase in Joseph. Ant. 10:3, 1. It never has the sense of semblance. Moreover, it is impossible to abstain from everything that looks like evil.
Of evil (πονηροῦ)
To be taken as a noun; not as an adjective agreeing with εἴδους form (from every evil form). The meaning of πονηρός in N.T. cannot be limited to active evil, mischief, though it often has that sense. The same is true in lxx, where it sometimes means grudging or niggardly. See Sir. 14:4, 5; 34:23.