NA, N.A., Na, nA or n/a may refer to:
==Chemistry and physics== Sodium, symbol Na, a chemical element Avogadro constant (NA) Nucleophilic addition, a type of reaction in organic chemistry Numerical aperture, a number that characterizes a range of angles in an optical system nA, the symbol for nanoampere Naturally aspirated engine
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).