ex·pand 
(ĭk-spănd)
(ĭk-spănd)v. ex·pand·ed, ex·pand·ing, ex·pands
v.tr.
1. To increase the size, volume, quantity, or scope of; enlarge: expanded her store by adding a second room. See Synonyms at increase.
2. To express at length or in detail; enlarge on: expanded his remarks afterward.
3. To open (something) up or out; spread out: The bird expanded its wings and flew off.
4. Mathematics To write (a quantity) as a sum of terms in an extended form.
v.intr.
1. To become greater in size, volume, quantity, or scope: Air expands when heated. This critic's influence is expanding.
2. To speak or write at length or in detail: expand on a favorite topic.
3. To open up or out; unfold: The chair expands to form a daybed.
[Middle English expanden, to spread out, from Latin expandere : ex-, ex- + pandere, to spread; see petə- in the Appendix of Indo-European roots.]
ex·panda·ble adj.
ex·pander n.