[more peculiar; most peculiar]

1 : not usual or normal : STRANGE

It seems peculiar that he would leave town and not tell anybody.

The dog’s peculiar behavior worried them.

She got a peculiar feeling when the phone rang.

She had a peculiar expression on her face.

2 : not used before a noun, British, informal : not well : somewhat ill

He’s feeling peculiar.

peculiar to

of, relating to, or found in (only one person, thing, or place)

a custom peculiar to America  [=a custom that is found only in America]

— peculiarly adverb

The movie has a peculiarly  [=distinctively, uniquely, particularly]  American quality.

He’s been behaving peculiarly.  [=(more commonly) strangely, oddly]