Defining Concealed

From Calguns Wiki

California Law does not define concealed.

Penal Code 12025 defines the crime of carrying a concealed firearm:

12025.  (a) A person is guilty of carrying a concealed firearm when
he or she does any of the following:
  (1) Carries concealed within any vehicle which is under his or her
control or direction any pistol, revolver, or other firearm capable
of being concealed upon the person.
  (2) Carries concealed upon his or her person any pistol, revolver,
or other firearm capable of being concealed upon the person.
  (3) Causes to be carried concealed within any vehicle in which he
or she is an occupant any pistol, revolver, or other firearm capable
of being concealed upon the person.

Section (f) does say

  (f) Firearms carried openly in belt holsters are not concealed
within the meaning of this section.

Since the Legislature has not defined concealed, it is reasonable to follow the procedure used by the California Court of Appeal in People v. Clark (1996) 45 Cal.App.4th 1147 , 53 Cal.Rptr.2d 99 and cite a definition from Webster's Ninth New Collegiate Dictionary (1983)

conceal 1: to prevent disclosure or recognition of
        2: to place out of sight.

Penal Code 12001 has some related definitions:

12001.  (a) (1) As used in this title, the terms "pistol,"
"revolver," and "firearm capable of being concealed upon the person"
shall apply to and include any device designed to be used as a
weapon, from which is expelled a projectile by the force of any
explosion, or other form of combustion, and that has a barrel less
than 16 inches in length. These terms also include any device that
has a barrel 16 inches or more in length which is designed to be
interchanged with a barrel less than 16 inches in length.
  (2) As used in this title, the term "handgun" means any "pistol,"
"revolver," or "firearm capable of being concealed upon the person."

As a guide to governing one's behavior, taking the 'common understanding' of the term as correct is simplest.