Synonyms: concern, headache, vexation, worry
Definition: something or someone that causes anxiety; a source of unhappiness
Usage: New York traffic is a constant concern; it's a major worry
Similar words: negative stimulus
Definition: a stimulus with undesirable consequences
Synonyms: cephalalgia, head ache, headache
Definition: pain in the head caused by dilation of cerebral arteries or muscle contractions or a reaction to drugs