GMAT Vocabulary Flash Cards @ englishpdf.com and englishteststore.com File 325 impregnable (adj) That can not be taken by assault impregnate (v) To make pregnant impromptu (n) Anything done or said on the impulse of the moment improper (adj) Not appropriate, suitable, or becoming impropriety (n) The state or quality of being unfit, unseemly, or inappropriate improvident (adj) Lacking foresight or thrift improvise (v) To anything extemporaneously or offhand imprudent (adj) Heedless