>>2172404A "cake" has never been purchased. Never eaten, never married. It's possible for them to have had sexual intercourse, but not necessarily likely, and some might try to define them as virgins.
1) CANNOT be married. NEVER married.
2) Usually a virgin, not required
3) There's usually a reason they're not taken and it has to do with their personality, fetish or quirk (in manga/anime, they're still hot as fuck, though)
A "MILF" literally has to have been fucked. They are literally a "Mom I'd Like to Fuck" and you can't really be a mom without semen. Can't be a MILF if they are barren and never had a children. They're usually married, too, but it's possible they're divorced or widowed.
1) MUST have a child.
2) They're generally at an age where their child is approaching, but hasn't quite reached, puberty. However, they can be as young as possible to bear a child (by definition) or, more commonly for "earliest", when they're still lactating.
3) Personality and body type are irrelevant. They are usually wide-hipped and large breasted, however, and display stereotypically motherly qualities.