In common parlance, a pensioner is a person who has retired, and now collects a pension. This is a term typically used in the United Kingdom; someone of pensionable age may also be referred to as an 'old age pensioner', or OAP. In the United States, the term retiree is more common. In many countries, increasing life expectancy has led to an expansion of the numbers of pensioners, and they are a growing political force.
A Political pensioner is a member of a formerly ruling dynasty who is paid a 'pension' (e.g. by the British raj) as a partial compensation for the income lost by not exercising an ancestral claim to a native throne
A Chelsea Pensioner is a retired British soldier who lives within the Royal Hospital