1. promote a product or event
use an interview/event to plug a new product
When used as a verb 'plug' can mean to block or fill in a cavity, gap or hole. 'Plug' can also be used in place of 'to fill', or mean to place something in a way so it fills a void or an opening. 'To plug' a product, person or service means to mention something publically intending to promote it. 'To plug' someone or something can also mean to shoot or hit someone or something. (This use you will come across more often in American contexts.) To 'plug away at' something means to continue to do something difficult over time.
The noun 'plug' refers to any solid material used to block a gap or hole. The most common plug you will come across is a circular piece of rubber, metal or plastic which is used to stop water escaping from a bath or sink. In America, a 'plug' can also refer to a babies soother or dummy. A plug is a solidified piece of lava found in the neck of a volcano. A plant which consists of roots covered in soil and used for planting is also a 'plug'. The part of electronics which connects the appliance to the mains is a 'plug', as well as the socket that an electrical cord goes in to. If you give a person or product a 'plug' it means you promote something by talking about it or mentioning it publically. Tobacco can be sold in a 'plug', which is a quantity of the product taken from a larger cake of tobacco usually used for chewing. (This is an archaic use of the word 'plug' and not often used anymore.) In fishing, a lure that has a hook attached is known as a 'plug'. A 'plug' is also an abbreviation of 'fireplug' which can refer to a fire hydrant. In North America, a 'plug' can mean an old or tired horse.