noun
mansion; large residence
Refers to a grand, spacious house, often implying luxury or high status. More formal than 豪邸 (ごうてい).
彼は郊外に大邸宅を構えている。
He owns a mansion in the suburbs.
邸宅 is a general term for a stately residence; 大邸宅 explicitly adds the sense of large scale.
Compound of 大 (だい, 'large') + 邸宅 (ていたく, 'residence, mansion'). The reading is on'yomi throughout.