(1) The usually latent sexual desire that a mother has for a son, or
(2) The domineering and intense, but non-incestuous love that an affect-hungry mother has for an intelligent son, which may be coupled to an absent or weak father figure.
Jocasta of Greek mythology was the mother of Oedipus and Queen consort of Thebes; Laius was his father and King of Thebes. Whilst Jocasta was pregnant with Oedipus, Laius consulted an oracle who said the baby would grow up, kill him, marry Jocasta and have children by her. So Laius bundled up Baby Oedipus and had a servant walk the bundle up a mountain and abandon it. The servant didn’t follow orders (you couldn’t get good help back then, either) and instead gave the baby to a shepherd, who raised the child as his own for 19 years.
Oedipus, now a young man, consulted with another oracle, who said the same thing, to wit, that he would dice dad and marry mum. Thinking that El and La Shepherd were his paternal and maternal units, he skedaddled to avoid fulfilling the prophecy. He goes to Thebes, has a fender bender with King Laius’ (his dad’s) chariot–what are the odds?–and in arguably the first road rage-related fatality–kills dad, leaving Thebes Kingless.
The townsfolk were further frazzled by the Sphinx, who wouldn’t let anyone into Thebes unless they answered her riddles. Oedipus cobbled together les mots juste, neutralising the Sphinx. For de-sphinxering the village green, Oedipus got the widowed queen. They marry; she pops 4 pups who in a court of law–now pay attention–are both her kids and grand kids; the whelps could in turn call her mum and nan–Nanomum?
Jocasta was thus both wife and mother, as predicted by the oracle (the Greeks really know how to spin a plot, eh?). Eventually they both sort out the details, at which point she hangs herself; Oedipus gouges out his eyes and wanders exiled in the wilderness with one of his daughters/sisters, Antigone…but not forgotten.