Mere means nothing more than what is stated. Only that, and less than you might have thought.
It always goes before the noun and it is there to diminish, so a mere child, a mere formality and a mere three pounds all say that the thing is smaller or slighter than expected. That belittling job is the whole word. The adverb merely means simply or only, and it is far commoner. There is an unrelated old noun, since a mere is a lake, which survives in place names like Windermere.
1adjectivemereNothing more than the thing stated.
“It was a mere twenty minutes from the station.”
Mere began as a boundary. Old English ġemǣre meant a limit or a border, from a root meaning to fence, so the word once marked the edge of a thing rather than making light of it.
Proto-Indo-European
*mer- — to sparkle, gleam
Latin
merus — pure, unmixed, undiluted
Old French
mier
Anglo-Norman
meer
Middle English
mere
English, today
mere
From Middle English mere, mer, from Anglo-Norman meer, from Old French mier, from Latin merus (“pure, unmixed, undiluted”), from Proto-Indo-European mer- (“to sparkle, gleam”). Cognate with Old English āmerian, āmyrian (“to purify, examine, revise”). The Middle English word was perhaps influenced by or conflated with sound-alike Middle English mere (“glorious, noble, splendid, fine, pure”), from Old English mǣre (“famous, great, excellent, sublime, splendid, pure, sterling”), from Proto-West Germanic mārī, from Proto-Germanic mērijaz.
Etymology from Wiktionary, CC BY-SA