- factoraside from its technical senses, means ‘a fact or circumstance that contributes to a result’, and the notion of cause lies at the heart of its use, as in Gladstone's sentence (1878) The first factor in the making of a nation is its religion. A modern example of its proper use is:
• Other factors can alter the Earth's climate from millennium to millennium and decade to decade —C. Tudge, 1991.In recent years, however, factor has become widely used in a weakened meaning ‘consideration, aspect, feature’ with little or no notion of causality:
• A very important factor in the teaching of tennis is the value of practice once the lesson is over —Tennis World, 1991.A new use dating from the 1980s involves a preceding noun as a defining word (originally the Falklands factor, then with successive connotations the Iraq factor) to denote an event which is considered to have a significant effect on the fortunes or politics of a country, political party, etc.:
• The continuation of the Iraq factor, uncertainty over the general economic situation and shaky stock markets all play their part —Birmingham Post, 2003.The feel-good factor is a feeling of material security in society, which occasionally yields to the feel-bad factor.The flagging fortunes of factor as a verb have been boosted with the evolution of the phrasal verb factor in, meaning ‘to include (a factor) in an assessment, plan, etc.’:
• All the political and military variables should be factored in before Israel decides on a response —Los Angeles Times, 1991.It originated in business talk in AmE and has spread rapidly to British use, even achieving some general currency; factor out is also occasionally found:
• Busy lifestyles have created buildings which have factored out healthy living —Guardian, 2005.
Modern English usage. 2014.