Persevere comes from the Latin words "per" and "assevero". Per means" through (space) or during (time)". Assevero means to "act earnestly, assert strongly, be serious, and emphatically declare". www.latin-dictionary.org
When searching for word meanings, it helps to know the etymology. Etymologies are not definitions. They are word origins that help you understand the definition or connotation of a word. Use a combination of the definition and etymology to really understand a word.