mahā-bhūta: the 4 'primary elements', is another name for the 4 elements (dhātu) underlying all corporeality; s. dhātu.

Buddhist Dictionary, Manual of Buddhist Terms and Doctrines, by NYANATILOKA MAHATHERA

mahā-bhūta

Sanskrit term meaning the ‘great elements’. These are the four forces which constitute materiality, namely solidity, fluidity, heat, and movement, and which are commonly referred to as earth, water, fire, and wind. To these a fifth element, space (ākāśa) is often added and consciousness (vijñāna) is sometimes mentioned as a sixth item.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)