torch 
(tôrch)
(tôrch)n.
1.
a. A portable light produced by the flame of a stick of resinous wood or of a flammable material wound about the end of a stick of wood; a flambeau.
b. Chiefly British A flashlight.
2. Something that serves to illuminate, enlighten, or guide.
3. Slang An arsonist.
4. A portable apparatus that produces a very hot flame by the combustion of gases, used in welding and construction.
5. Longstanding unrequited romantic feelings for a person: My torch for her has finally gone out.
tr.v. torched, torch·ing, torch·es
Slang
Idioms: Slang
To cause to burn or undergo combustion, especially with extraordinary rapidity, force, or thoroughness.
carry a torch
To have longstanding feelings of love that are not requited: still carrying the torch for a man she knew in her twenties.
put to the torch
To destroy by fire; burn down.
[Middle English torche, from Old French, from Vulgar Latin *torca, alteration of Latin torqua, variant of torquēs, torque, from Latin torquēre, to twist; see terkw- in the Appendix of Indo-European roots.]