Formal/Neutral:
* Pretentious: This implies they put on a show of wisdom to impress others.
* Affected: This suggests they're trying to adopt a persona of wisdom, often in an unnatural way.
* Poser: This term implies they're merely mimicking wisdom without genuine understanding.
* Phony: This implies a lack of authenticity and an attempt to deceive.
* Self-important: This indicates they have an inflated sense of their own wisdom.
Informal/Negative:
* Wiseacre: This is a more informal term for someone who pretends to be wise, often with a sarcastic or humorous tone.
* Smart aleck: This term implies someone is being overly clever or sarcastic.
* Know-it-all: This describes someone who believes they are always right and knowledgeable, even when they're not.
* Windbag: This term emphasizes their tendency to talk at length about things they don't fully understand.
More specific terms:
* Sophist: This term refers to a person who uses clever arguments or deceptive reasoning to persuade others, regardless of the truth.
* Quack: This term is often used for someone who pretends to have medical knowledge, but in a broader sense, can refer to anyone who pretends to be knowledgeable about something they're not.
The best word to use depends on the specific situation and the tone you want to convey.