Webster's Revised Unabridged Dictionary · 1913

Appall

Appall ({not transcribed}) , transitive verb

[Old French appalir to grow pale, make pale; a (Latin ad) + pâlir to grow pale, to make pale, pâle pale. See Pale, a., and compare Pall.]

1.
To make pale; to blanch. [Obsolete]
The answer that ye made to me, my dear,... Hath so appalled my countenance. — Wyatt
2.
To weaken; to enfeeble; to reduce; as, an old appalled wight. [Obsolete] — Chaucer
Wine, of its own nature, will not congeal and freeze, only it will lose the strength, and become appalled in extremity of cold. — Holland
3.
To depress or discourage with fear; to impress with fear in such a manner that the mind shrinks, or loses its firmness; to overcome with sudden terror or horror; to dismay; as, the sight appalled the stoutest heart.
The house of peers was somewhat appalled at this alarum. — Clarendon

Appall , intransitive verb

1.
To grow faint; to become weak; to become dismayed or discouraged. [Obsolete] — Gower
2.
To lose flavor or become stale. [Obsolete]

Appall , noun

Terror; dismay. [Poet.] — Cowper