rule out: meaning and explanation
If you rule something out, then you eliminate it as an option and no longer consider it. e.g. I think we can rule out having the Christmas party on the roof terrace of The Shard – we just can’t afford it this year.
Ruling something out can also be used to say that something is impossible, or definitely won’t happen. e.g. During his speech, the Prime Minister ruled out the possibility of stepping down before the next election.
This phrasal verb is often used with the noun ‘possibility’ – to rule out the possibility of something happening.
This phrasal verb is often use negatively to say that something is still an option or a possibility. e.g. I think it is unlikely that we’ll be making additional redundancies this year, but I wouldn’t rule it out completely.
Have a go at these micro-dictation exercises to hear this expression being used in context – how much can you understand?
Accent: North America
About the sentence
…someone started the fire deliberately…
Deliberately is a useful synonym of on purpose or intentionally.