square peg in a round hole

Fig. someone who is uncomfortable or who does not belong in a particular situation. (Also the cliché: trying to fit a square peg into a round hole, trying to combine two things that do not belong or fit together.) I feel like a square peg in a round hole at my office. Everyone else there seems so ambitious, competitive, and dedicated to the work, but I just want to make a living. Trying to teach me math is like trying to fit a square peg into a round hole. I'm convinced my brain is not built right to understand algebra.

Also, round peg in a square hole. A misfit, especially a person unsuited for a position or activity. For example, Ruth doesn't have the finesse for this job; she's a round peg in a square hole. This idiom, with its graphic image of something that cannot fit, dates from about 1800.

A misfit.

A misfit. Its origin attributed to the 19th-century British philosopher and cleric Sydney Smith, the phrase has been used in a business context to describe someone who doesn't fit in to corporate culture, isn't a team player, and therefore stands little chance of corporate advancement.