Welsh deity-mother of Lleu Llaw Gyffes and Dylan ail Don in the canonical-Mabinogion Fourth Branch. Her name "silver-wheel" (arian "silver" + rhod "wheel") and the medieval-Welsh stellar-toponym Caer Arianrhod ("Castle of Arianrhod" — the medieval-Welsh name for Corona Borealis) anchor her cosmic-feminine deity-figure. The canonical-Welsh magic-wand magical-conception scene: Math's magic-wand virginity-test caused her to "drop" two children — Dylan ail Don (who immediately swam into the sea) and a small object (Lleu) which Gwydion gathered up and raised. Per the canonical-scholarly reading per Gruffydd 1928 and Williams 1951, the dropping reflects implicit-incestuous union with her brother Gwydion; the Fourth Branch text keeps this implicit-not-explicit. When Gwydion brought Lleu to her court, refused to recognize him; placed three tyngedau on him (no name unless she names him; no arms unless she arms him; no wife of any race on this earth) — all three circumvented by Gwydion and Math's combined trickery and conjuration. The canonical-Welsh cursing-mother-of-the-rejected-son narrative-paradigm. Her canonical-Mabinogion deity-mother role classifies her as deity-tier and makes her the divine parent for Lleu's strict ½-demigod classification.