Tortoiselike is an adjective that describes someone or something that moves slowly and steadily, resembling the slow pace of a tortoise. The antonyms for tortoiselike would, therefore, be words that describe the opposite of this trait. Some examples of antonyms for tortoiselike are fast, quick, swift, rapid, and speedy, which all describe something or someone that moves quickly. Agile, brisk, nimble, sprightly, and supple are other antonyms that connote quickness and flexibility, unlike the slow or clumsy pace of a tortoise. Choosing the right antonym for tortoiselike depends upon the context in which it is used.