a set of tools, instruments or equipment put together for a purpose

equipment with a purpose

a question, person, thing, circumstance, that is puzzling

mystery

anything that gives a reason for believing, that makes clear or proves, something

proof

a serious mental illness causing great excitement, violence

fixation, madness

something of which the cause or origin is impossible to explain or understand

puzzle, secret

(an example of) evidence that is sufficient to show that something is a fact

evidence, authentication

something that annoys

incitement, stimulus

a state of (excited or worried) uncertainty

anticipation