Cruciform means having the shape of a cross.
It is a common description of Christian churches, which are usually, though not exclusively, built with a layout comprising
An East end, containing an altar and often with an elaborate, decorated window, through which light will shine in the early part of the day.
A West end, which sometimes contains a font, being a large decorated bowl, in which water can be firstly, blessed (dedicated to the use and purposes of God) and then placed upon infant or older believers as a sign of their dedication.
North and South Transepts, being "arms" of the cross and often containing rooms for gathering, small side chapels, or in many cases, the other necessities of worship - an organ and toilets.
Cruciform designs became the more popular form for Cathedrals beginning in the 9th century owing to the development of capping box-shaped structures with a central dome. Until this time, circular churches predominated.
Although the term "cruciform" is strongly associated with Gothic design, the term may be applied to any similarly laid-out buildings, even non-religious ones.
See also cathedral diagram