GC: npl

S: http://www.socwork.net/sws/article/view/227/458 (last access: 16 July 2012); https://www.mi5.gov.uk/home/the-threats/terrorism/threat-levels.html (last access: 2 September 2014).

N: Old English þreat “crowd, troop,” also “oppression, coercion, menace,” related to þreotan “to trouble, weary,” from Proto-Germanic *thrautam (cognates: Dutch verdreiten, German verdrießen “to vex”), from PIE *treud- “to push, press squeeze” (cognates: Latin trudere “to press, thrust,” Old Church Slavonic trudu “oppression,” Middle Irish trott “quarrel, conflict,” Middle Welsh cythrud “torture, torment, afflict”). Sense of “conditional declaration of hostile intention” was in Old English.

S: OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=threat&searchmode=none (last access: 5 September 2014)

SYN:
S:

CR: ill-treatment, violence, vulnerability.