20:1 bet

"...head of the CMS group, has offered colleagues 20:1 against the particle’s existence, with payment in bottles of decent French wine. So far, no takers. “I’m not finding anyone among my colleagues who wants to accept my bet,” he says. “I am betting against it, but I would gladly lose.” (From The Guardian.)

Does the bet in question ("20:1") mean that the head of the CMS group pays for 20 bottles of wine if he loses and gets one bottle if he wins the bet?