The noun prayer has 5 senses (first 4 from tagged texts)
1. (5) prayer, supplication -- (the act of communicating with a deity (especially as a petition or in adoration or contrition or thanksgiving); "the priest sank to his knees in prayer")
2. (4) prayer, petition, orison -- (reverent petition to a deity)
3. (2) entreaty, prayer, appeal -- (earnest or urgent request; "an entreaty to stop the fighting"; "an appeal for help"; "an appeal to the public to keep calm")
4. (1) prayer -- (a fixed text used in praying)
5. prayer, supplicant -- (someone who prays to God)