This root form (lemma) is used in 2 different forms in the NT: ἀτμίδα (AFS), ἀτμὶς (NFS).
It is glossed in 2 different ways: ‘a vapour’, ‘vapour’.
OET ACTS 2:19 Greek word=ἀτμίδα (atmida) Morphology=AFS English gloss=‘vapour’ SR GNT ACTS 2:19 word 18
OET JAM 4:14 Greek word=ἀτμὶς (atmis) Morphology=NFS English gloss=‘a vapour’ SR GNT JAM 4:14 word 13