What it means
びる is a suffix that forms a verb meaning “to appear or seem like” the noun it follows, often suggesting an adult-like, rural, old-fashioned, or otherwise characteristic quality. It is most common in established expressions and describes an outward impression or a change toward that quality rather than a simple identity. The resulting verb conjugates normally, as in 大人びた and 大人びている.
Usage note
びる is not freely attached to every noun; many uses are conventionalized compounds such as 大人びる, 古びる, and 田舎びる. Do not confuse it with っぽい, which is more productive and often more colloquial.
How to use it
その少年は、制服を着ると実年齢より大人びます。
When wearing a uniform, that boy appears older than his actual age.
その少年は、制服を着ると実年齢より大人びる。
When wearing a uniform, that boy appears older than his actual age.
Example sentences
図書館の木製の机は古びていたが、毎日丁寧に手入れされているため、今でも使いやすい。
Although the wooden desk in the library had grown old, it is still easy to use because it is carefully maintained every day.
高校生になった妹は、以前より大人びて見える。
My younger sister, who has become a high school student, appears more mature than before.
山あいの