in-filtrate (verb) infiltrate: creep in
Sinonime: astute, bullheaded,
cool, hang tough, hard, hard-boiled, hard-nosed, headstrong, intractable, level-headed, locked in, mulish, obstinate, pertinacious, perverse, pigheaded, practical, pragmatic, rational, realistic, resolute, sensible, shrewd, sober, stand pat, tough, tough nut, unsentimental, unyielding, willful
Antonime: yielding