Verb (5-dan, る, intransitive)
1. to persevere; to persist; to keep at it; to hang on; to hold out; to do one's best
はい、これで頑張って！Here, use this and do your best!
2. to insist that; to stick to (one's opinion)
3. to remain in a place; to stick to one's post; to refuse to budge