シ, ただ.ならぬ, ただ.に

incomparable, merely

JLPT0 G13 S0 F5000

As per # (unify) + mouth → adverb inflecting the tone of voice to suggest *only* (← united; no other) → *merely*. A variant form, , appears in many derivative characters, including 適, , and .

[Full Kanji Etymology List]