The Wolves winger missed the best part of two campaigns due to assorted injuries, but returned to first-team action at the end of last season.
Despite starting two Premier League games so far this term, he has opted to join the Hornets to gain some much-needed match practice.
He told Hornets Player: "I'm fully fit and feeling great now, but you can't replicate that match sharpness you only get with a run of starts.
"When you've been out as long as I was, there's plenty of time to reflect on what you've done and what you'd like to do.
"I'm raring to go and I'm looking forward to a run of games, and I'm very thankful Watford have given me a chance to come to them and get going."
Source: Team Talk
Source: Team Talk