from
The Collaborative International Dictionary of English v.0.48
Pencil \Pen"cil\, v. t. [imp. & p. p. {Penciled}or {Pencilled};
p. pr. & vb. n. {Penciling} or {Pencilling}.]
To write or mark with a pencil; to paint or to draw.
--Cowper.
[1913 Webster]
Where nature pencils butterflies on flowers. --Harte.
[1913 Webster]
{pencil in} to write (a tentative appoinment) on an
appointment calendar, so as to reserve time, but to allow
the appointment to be readily canceled and replaced with
another; -- also used figuratively, with other means of
recording appointments. The notion being that something
written in pencil can be more easily changed than
something written in ink. The phrase is commonly used in
the early stages of organizing a meeting of multiple
persons, before it is known whether all attendees will be
free at the suggested time.
[PJC]