Full Idea
Aristotle says there are two proper uses of the term 'being': firstly, for whatever falls into one of Aristotle's ten basic categories of thing, and secondly for whatever makes a proposition true.
Gist of Idea
Being is either what falls in the categories, or what makes propositions true
Source
report of Aristotle (Metaphysics [c.324 BCE], 1017a21-35) by Thomas Aquinas - De Ente et Essentia (Being and Essence) p.91
Book Reference
Aquinas,Thomas: 'Selected Philosophical Writings', ed/tr. McDermott,Timothy [OUP 1993], p.91
A Reaction
The first sounds circular, because the categories must be selected for whatever has being (see Idea 11196). The first sounds Fregean, and very congenial to modern philosophy (though you need a clear notion of 'true'). Or it is being as truth-makers.
Related Idea
Idea 11196 Essence is something in common between the natures which sort things into categories [Aquinas]