Mere and Merely are not extremely common but when these words come up, people have a hard time understanding what they mean. In general, you can replace them with “only”.
They can be put to good use in academic writing!
Something small or insignificant; Nothing more than what is mentioned (only)
The mere idea made me shudder.It was a mere formality.With the merest suggestion of corruption, the entire project will be shut down.
nothing more or less (only)
He’s merely a secretary.I was merely suggesting that…This merely aggravates the problem.This procedure is merely a matter of form.It was merely a coincidence; there was no causal relationship.