Merely, adv.
1. Purely; unmixedly; absolutely. Ulysses was to force forth his access, Though merely naked. Chapman.
2. Not otherwise than; simply; barely; only. Prize not your life for other ends Than merely to obige your friends. Swift.
Syn. -- Solely; simply; purely; barely; scarcely.
Shades of meaning
Fernald has no entry of its own for merely; he lists it under but.
He lists it without comment; the entries above explain its neighbors.