obscurement

[Clai Rice]

A colleague and his student, a local policeman, disagreed on the word
"obscurement" this morning.  My colleague didn't find it in any of his desk
dictionaries, nor in AHD4, nor Merriam-Webster Online.  Hyperdictionary.com
records this from Webster's 1913: "n. The act of obscuring, or the state of
being obscured; obscuration. --Pomfret."  It is listed with three
attestations in OED Online as "rare," defined as "= obscuration; production
of obscurity."  The cop produced a "motor vehicle incident report" that
included a category called "visual obscurements" for indicating that
roadside objects like parked cars, trees, signs, trucks, might have
contributed to an "incident".  Googling on "vision obscurement" (quoted)
yielded 55 hits, all from traffic-related documents. Searching on
"obscurement" produced an inordinate number of hits on "D and D"-type gaming
documents.

In moving from "rare" to "specialized", the word seems to have undergone a
slight extension. Both types of document provide examples that support the
definition "act of obscuring or the state of being obscured":

http://www.weberandnierenberg.com/verdicts02.html
that the van caused an obscurement for plaintiff and the uninsured motorist

But both types also include many examples suggesting metonymic extension so
that the thing producing an obscurement can also be called an obscurement:

http://www.cityofportsmouth.com/agendas/2003/ts/ts061903m.pdf
Police Lt. Fred Hoysradt stated that the fence on the property as you leave
Mechanic St. to Marcy St. is a visual obscurement to on-coming traffic.

http://rt000pui.eresmas.net/Battletech/3025Revised/Lights/Ostscout/Ostscout.
html
If different types of obscurement conceal the target, effects are
cumulative.

http://www.cs.pdx.edu/~kenstcyr/System/hazards.html
Light Conditions
The following table gives visibility ranges in meters for various light and
weather conditions. Light obscurement includes rain, light fog or snowfall.
Heavy obscurement includes heavy rains, heavy fog, or blizzard. Dense
obscurement is thick smoke or peasoup fog.

http://www.dot.state.ia.us/crashanalysis/imw_manual/dataavailability.htm
[form fields for accident reports]

Vision Obscurement of Driver of Vehicle 1 [definition 1]
Field 23/D1 VISION
Indicates whether the vision of the driver for the 1st vehicle indicated as
being involved in the crash was obscured and, if so, by what.
1 = Not obscured
2 = Trees/crops
3 = Buildings
4 = Embankments
5 = Sign/billboard
6 = Hillcrest
7 = Parked vehicles
8 = Moving vehicles
9 = Person in/on veh
10 = Sun/Headlights
11 = Frosted window
12 = Blowing snow
13 = Fog/smoke/dust
14 = Other obscurement  [extended]
0 = Unknown

--Clai Rice