definition of
headache

[1] #1 headache n. [concern, worry, vexation] something or someone that causes anxiety; a source of unhappiness; "New York traffic is a constant concern"; "it's a major worry". wn

[2] #2 headache n. [head ache, cephalalgia] pain in the head caused by dilation of cerebral arteries or muscle contractions or a reaction to drugs. wn