These words refer to what arouses interest, motivates to action or is satisfying and invigorating. Stimulate is the most general of these, applying in all three situations: a remark that stimulated my curiosity; a crisis that finally stimulated the government into acting; an impromptu jazz session that everyone present found to be extremely stimulating . Excite also can apply to the arousal of interest, but in this sense it has a more formal tone than stimulate : a book that excited a great deal of an intense emotional response: They feared that the visitors would excite the patient too much; His raw anti-Semitism excited the crowd to fury.

Enliven applies solely to what is both arousing and invigorating: an outspoken couple who could always be counted on to enliven a dull party; open-air sculpture to enliven the grey uniformity of the city. Galvanize , by contrast, applies strictly to setting something decisively in motion, particularly after a period of vacillation or disorganization: new supporting troops to galvanize our flagging counter-offensive; a tragedy that galvanized the government into action.

Titillate and whet also apply exclusively to one aspect of stimulate , indicating an initial arousal of interest or desire. Most concretely, whet applies to an appetite for food: hors d'oeuvres to whet the appetite. Similarly, when the word applies in other contexts, it usually suggests partaking of a small sample that leads to a desire for some larger portion: government action that only whetted the desires of Aborigines for full equality; an opening chapter that whets the reader’s interest in reading on. By contrast, titillate need not suggest any actual sampling at all. While it can function like whet in the context of food, it more often suggests a tempting action achieved through allusion, insinuation or promises of what is to come. It implies raising eager expectations of whatever kind, whether or not these promises are later fulfilled.

• The appetizer was delicious and titillated the gourmet’s palate; Rumours of secret information on the assassination titillated the curiosity of the public; titillating illustration on the covers of pornographic novels.