inept, inapt

Inept or inept means without skill; incompetent --
He is not only inept, but also unreliable.
She is inept at managing money; she can never remember what she spent.

Inapt or inapt means not suitable; inappropriate --
His inapt comment made everyone uncomfortable.
The project name is inapt, and possibly offensive. Change it.

Now that you know that, you can say --
"He is socially inept; his inapt remark may cost us the account."

Note -- "unapt" means not suitable--
The post was unapt, but certainly not offensive.

Unapt may also mean not likely; unlikely --
He is unapt to waste time on such a trivial matter.

Unapt may also mean lacking skill or capacity for a given task --
He is a remarkably unapt pupil; he should study something else.