- concern, worry, headache, vexation - something or someone that causes anxiety; a source of unhappiness; "New York traffic is a constant concern"; "it's a major worry"
--1 is a kind of negative stimulus
--1 has particulars:bugaboo; burden, load, encumbrance, incumbrance, onus; business - headache, head ache, cephalalgia - pain in the head caused by dilation of cerebral arteries or muscle contractions or a reaction to drugs
--2 is a kind of ache, aching
--2 has particulars:histamine headache, cluster headache; migraine, megrim, sick headache, hemicrania; sick headache; sinus headache; tension headache