I don't understand your question. If it appears in the combustion reaction, it is being formed. Why should there be a meaning associated with that ?
If it appears in a textbook or in an article, you might help us assist you by quoting some more context.
OH- is usually a negatively charged radical. ##\ ## -OH can mean a lot of things, including OH-
H2O2 is hydrogen peroxide. -H2O2 could be a doubly negative radical H2O22-
No, not meaning like that
For example appearance of CH2O shows cool flame...