Gradually, little by little, inch by inch, gently.
( incision ), by twelfth, inch by inch, little by little
(sensim), gradually, gently, feeling ones way, tentatively, inch by inch, carefully
Inch, pollicis ,
( verb, move slowly and carefully for a specified direction : edge),

Inch,
Pollicis , uncia (noun)
Once, inch, twelfth part
1) use of linear measures, equal to one twelfth of a foot
2) a unit used to express other qualities, in particular