An alternative spelling of 'arrester'; a person or device that stops or arrests something.
Variant spelling of arrester using -or instead of -er. Both -or and -er suffixes create agent nouns meaning 'one who does,' though -or is more common in technical/mechanical contexts.
Different fields prefer different spellings: electrical engineers often write 'arrestor' while general English prefers 'arrester'—it's a tiny example of how specialized vocabularies develop their own conventions.
Complete word intelligence in one call. Free tier — 50 lookups/day.