MILF, acronym for “Mother/Mom/Mum I’d Like to Fuck”, is a colloquial term popularized by the 1999 film American Pie. It originally referred to a sexually attractive mother with at least one child in his/her teens and who is usually at the same age as the person using the term.
In pornography, it is used for female performers past the median maximum age (30–35 years) and even younger performers with substantially older looks or presented as such may also be featured as MILFs who are seducing or are seduced by much younger male performer. The ambiguous conventions of the industry have given way to oxymoron uses such as teen MILF. For older than 50 years performers (so called grannies or golden age) sometimes used the much less common epithet GILF (“Grandmother/Grandma I’d Like to Fuck”).
Performers who fall in the mature category (older than 30–35 years) must not be considered as a subset of the category MILF, if they not intercourse with much younger person at the age 18–22 years (high school or college students), — they must be considered as just sexy aged but experienced in sex women who are ready for sexual adventures. For case of horny mature woman who’s seducing younger (but not much younger as for MILFs) males is used term cougar in sense: “a middle aged seductress is hunting for a fresh meat”, i.e. horny middle aged housewives are usually play role of cougars, but sexy aged teachers are MILFs (of course, if their students are properly aged).
Nevertheless, the term MILF may be effectively seen in contrast with the formerly ubiquitous mature niche that usually caters to anililagnia (old woman fetish) of its viewers, instead of emphasis on sexual attractiveness despite advanced age. But after it’s popularity the term MILF is often used in sense of cougar or just in sense of mature, not in it’s own.