unapproachable, a. inaccessible, [distant].
unarmed, a. defenseless, [unguarded], unprotected.
unasked, a. unsolicited, [voluntary], [free-will].
unassailable, a. impregnable, [invincible], [secure], invulnerable.
unassorted, a. [mixed], [promiscuous], indiscriminate.
unatonable, a. inexpiable, irremissible.
unattainable, a. unachievable, [impracticable], [impossible].
unauthentic, a. [spurious], supposititious, [uncanonical], apocryphal, fictitious.
unavailing, a. [futile], [nugatory], ineffectual, [abortive], [vain], [bootless].
unavoidable, a. inevitable, [unpreventable], ineludable.