an object that one need not, cannot, or does not wish to give a specific name to.
look at that metal rail thing over there
an inanimate material object as distinct from a living sentient being.
I'm not a thing, not a work of art to be cherished
an action, activity, event, thought, or utterance.
she said the first thing that came into her head
what is needed or required.
you need a tonic–and here's just the thing