1.NounA person paid to endorse a product while pretending to be impartial.
"carnival barkers and their shills, fleecing the rubes"
2.NounAny person enthusiastically endorsing a product; especially, one who is getting paid for the endorsement.
"On the screen, there was that quack again, playing the shill for yet another drug company."
3.NounAn accomplice at a confidence trick during an auction or gambling game, such as an accomplice of the seller who bids to drive up the price.
"Sniping is necessary because if you bid before the last minute it just gives the shills more time to screw you over."
4.NounA house player in a casino.
5.VerbTo promote or endorse in return for payment, especially dishonestly; sometimes extended sarcastically even to those not paid but strongly biased in favor.
"That contractor seems to be shilling for a certain brand of building materials.; That contractor seems to be shilling that specific epoxy."