We don't have synonyms for heat lightning yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are sheet lightning and bead lightning.
We don't have any synonyms for heat lightning yet.
(n) :
Lightning and/or thunder which the observer attributes to heat rather than a storm (e.g. because the storm/rain is too distant to be seen, or because there is no rain, as with dry lighting).
(n) :
(in particular) Visible lightning that occurs too far away for the resulting thunder to be audible by the observer.
(n) :
(less commonly) Thunder that is heard without lightning being seen by the observer; heat thunder.
(n) :
Lightning and/or thunder which the observer attributes to heat rather than a storm (e.g. because the storm/rain is too distant to be seen, or because there is no rain, as with dry lighting).
(n) :
(in particular) Visible lightning that occurs too far away for the resulting thunder to be audible by the observer.
(n) :
(less commonly) Thunder that is heard without lightning being seen by the observer; heat thunder.