Impregnable. Invincible, unassailable, invulnerable, immovable, inexpugnable, secure, tenable, irrefragable.
Ant. Pregnable, weak, exposed, defenseless, expugnable.
Impregnate. Fecundate, imbue, infuse, tincture, saturate, fill, fertilize; mix, combine, insert, steep, vivify, teach.
Ant. Remove, evolve, extricate, separate, destroy, quench, extinguish, be studious, learn.
Impression. Printing, stamping, imprinting; stamp, impress, brand; mark; sensation, effect, influence; notion, idea, opinion, fancy.
Ant. Concept, apprehension, comprehension.
Impressive. Affecting, touching, moving, stirring, powerful, striking, overpowering; forcible, solemn, imposing, important.
Ant. Weak, feeble, vapid, tame, unimpressive, dry, insignificant.
Improve. Mend, gain, become better, get on, gain ground; increase, rise, be enhanced; better, amend, ameliorate, rectify; progress; avail one’s self of, use, make productive; correct, reform.
Ant. Debase, deteriorate, vitiate, spoil, mar, impair, injure, depress.