What is the meaning of lour?

verb

• Set lower.
  • usage: "lower a rating"; "lower expectations"
  • synonyms: lower
• Make lower or quieter.
  • usage: "turn down the volume of a radio"
  • synonyms: turn down, lower
• Look angry or sullen, wrinkle one's forehead, as if to signal disapproval.
  • synonyms: frown, glower, lower