Final answer:
An expression that becomes cliché has lost its novelty and originality through overuse, such as 'Think outside the box.' To ensure language remains vibrant, it's advisable to avoid clichés and follow Mark Twain's advice by using adjectives sparingly.
Step-by-step explanation:
An expression that was once innovative but has lost its novelty due to overuse is termed a cliché. This happens when a phrase or idea is used so frequently that it loses originality and impact, becoming mundane and uninspiring. The saying 'Think outside the box' is an example of such a cliché; it was initially used to encourage creative thinking beyond conventional boundaries but is now so common that it often fails to stimulate the intended thoughtfulness.
Clichés can make communication dull and may suggest a lack of creativity in the speaker or writer. Note the advice of Mark Twain regarding the use of adjectives, which if overused can become tiresome and weaken the language. Instead, exercise discretion with language choices to maintain the strength and vividness of the message.
Expressions like 'What's on your mind?' or 'Great minds think alike!' are also considered clichéd as they are overused phrases in the English language. To avoid falling into the trap of clichés, one should strive to find fresh, original ways of expressing thoughts and ideas.