inch 1 
(ĭnch)
(ĭnch)n. Abbr. in or in.
1. A unit of length in the US Customary and British Imperial systems, equal to 1/12 of a foot (2.54 centimeters). See Table at measurement.
2. A fall, as of rain or snow, sufficient to cover a surface to the depth of one inch.
3. A unit of atmospheric pressure that is equal to the pressure exerted by a one-inch column of mercury at the earth's surface at a temperature of 0°C.
4. A very small degree or amount: won't budge an inch.
intr. & tr.v. inched, inch·ing, inch·es
Idioms: To move or cause to move slowly or by small degrees: inching along through stalled traffic; inched the chair forward.
every inch
In every respect; entirely: "Ay, every inch a king!" (Shakespeare).
inch by inch
Very gradually or slowly.
within an inch of
Almost to the point of: came within an inch of death.
[Middle English, from Old English ynce, from Latin ūncia, one twelfth of a unit; see oi-no- in the Appendix of Indo-European roots.]