What is so to speak?

"So to speak" is an idiomatic expression used in English to indicate that what you are saying shouldn't be taken literally, but rather figuratively or metaphorically. It's often employed to clarify that a phrase or word is being used in a non-standard, unconventional, or creative way.

For example, you might say, "He's the backbone of our team, so to speak," meaning the person is very important to the team, rather than literally comparing them to a spine.

This expression is commonly used in both spoken and written English and helps convey a more nuanced meaning, allowing the speaker to express ideas creatively or in a roundabout way without misleading the listener or reader.