to have being in the real world; to be
Do unicorns exist?
to have being in specified conditions
Some chemical compounds exist only in solution
to have life or the functions of vitality
One would rather exist, even in pain, than not exist — Dr Johnson
to live at an inferior level or under adverse circumstances
existing from one day to the next
[Latin exsistere to come into being, exist, from ex-1 + sistere to stand]