Not possible; that cannot be done or effected; that cannot exist or come into being; that cannot be, in existing or specified circumstances. Const. to…

(un-, prefix1 affix 1.)

Incapable of being accomplished or carried out; impracticable, impossible.

Not able to be (done); impossible. Obsolete.

Not performable; esp. impossible to perform or accomplish successfully.

That cannot be practised or effected in practice; impracticable. Also: that should not be practised. Cf. unpracticable, adj.

= unfeasible, adj.

(un-, prefix1 affix 1.)

Impracticable; impossible to fulfil or achieve in practice.

Not operable. Chiefly in medical contexts. Cf. inoperable, adj.

(un-, prefix1 affix 1b.)

That cannot be performed or rendered.

That cannot be performed or executed; unperformable.

Not practicable; that cannot be carried out, effected, accomplished, or done; practically impossible.

(un-, prefix1 affix 1b.)

That cannot be effected or carried out; impracticable.

That cannot be executed.

Not workable; not capable of being worked, put into operation or practice, etc.

Not practical; unpractical. Also = impracticable, adj.

(un-, prefix1 affix 1b.)

= impossible, adj.