A representation of a substance using symbols for its constituent elements WordNet 3.0 & Open English WordNet

In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus and minus signs. Wikipedia

An expression of the contents of a chemical compound Wikipedia Disambiguation

Compact notation for chemical compounds giving element symbols and counts, including empirical formulas, molecular formulas, and condensed formulas Wikidata

A formalization which provides information about the atoms that constitute a particular chemical compound, and how the relationship between those atoms changes in chemical reactions. OmegaWiki

A symbolic expression of the structure of a compound. Wiktionary