re·spond 
(rĭ-spŏnd)
(rĭ-spŏnd)v. re·spond·ed, re·spond·ing, re·sponds
v.intr.
1. To make a reply; answer: respond to an email.
2. To act in return or in answer: firefighters responding to a call. See Synonyms at answer.
3. To react to a stimulus or to a treatment, especially in a favorable way: tumors that responded to radiation.
v.tr.
To give as a reply; answer.
n.
Architecture
Architecture
A pilaster or half-pier engaged to a wall and carrying one end of an arch or groin, often at the end of an arcade.
[Middle English responden, from Old French respondre, from Latin respondēre : re-, re- + spondēre, to promise; see spend- in the Appendix of Indo-European roots.]
re·sponder n.