Source : Webster's Revised Unabridged Dictionary (1913)
Threaten \Threat"en\, v. t. [imp. & p. p. {Threatened}; p. pr. &
vb. n. {Threatening}.] [OE. [thorn]retenen. See {Threat}, v.
t.]
1. To utter threats against; to menace; to inspire with
apprehension; to alarm, or attempt to alarm, as with the
promise of something evil or disagreeable; to warn.
Let us straitly threaten them, that they speak
henceforth to no man in this name. --Acts iv. 17.
2. To exhibit the appearance of (something evil or
unpleasant) as approaching; to indicate as impending; to
announce the conditional infliction of; as, to threaten
war; to threaten death. --Milton.
The skies look grimly And threaten present blusters.
--Shak.
Syn: To menace.
Usage: {Threaten}, {Menace}. Threaten is Anglo-Saxon, and
menace is Latin. As often happens, the former is the
more familiar term; the latter is more employed in
formal style. We are threatened with a drought; the
country is menaced with war.
By turns put on the suppliant and the lord:
Threatened this moment, and the next implored.
--Prior.
Of the sharp ax Regardless, that o'er his
devoted head Hangs menacing. --Somerville.
Source : WordNet®
threatened
adj : (of flora or fauna) likely in the near future to become
endangered; "the spotted owl is a threatened species,
not yet an endangered one"