I can't understand him; he is really a queer fellow.

Solution (By Examveda Team)

Queer : strange; odd.
Strange : unusual or surprising; difficult to understand or explain.
Careless : not giving sufficient attention or thought to avoiding harm or errors.
Ordinary : with no special or distinctive features; normal.
Unusual : not habitually or commonly occurring or done.

Antonym of Queer is Ordinary