What does Blodwen mean?
From Welsh 'blodau' (flowers) + 'gwen' (white, blessed, holy), so 'white flowers' (or 'blessed flowers'). Known from Joseph Parry's 1878 Welsh opera 'Blodwen'.
What does Tanwen mean?
Modern Welsh name (from the 1960s) combining 'tan' ('fire') with '-wen', the feminine form of 'gwen' ('white, fair, blessed'). Usually glossed 'white fire', or 'holy fire' from the blessed/saintly sense of the suffix.