Intrusion. Encroachment, interference, intruding, obtrusion, infringement.
Ant. Withdrawal, removal, retirement, retraction.
Intuition. Apprehension, cognition, perception, beholding; instinct, insight, recognition.
Ant. Information, instruction, learning, experience, acquirement, induction.
Inundate. Flood, deluge, overflow, submerge, cover, overwhelm.
Ant. Drain, dry, reclaim, desiccate, parch.
Invade. Attack, infringe, violate, encroach on, trench upon; march into, enter in, assault, assail, occupy.
Ant. Abandon, relinquish, vacate, evacuate.
Invalid, a. Week, feeble, infirm, sick, frail; null, void; unsound, baseless, untrue, unfounded, fallacious.
Ant. Strong, well, healthy, vigorous; sound, legal, constitutional; legitimate, authorized; genuine, true, correct, exact.