fieldwork

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A temporary military fortification erected in the field.
2. n. Work done or firsthand observations made in the field as opposed to that done or observed in a controlled environment.
3. n. The collecting of sociological or anthropological data in the field.

Century Dictionary and Cyclopedia

1. n. In surv., physics, etc., work done, observations taken, or other operations, as triangulation, leveling, observing the stars for latitude, longitude, azimuth, etc., making geological observations, studying objects in their natural state, collecting specimens, etc., carried on in the field or upon the ground, even though indoors.
2. n. Milit., a temporary work thrown up by either besiegers or besieged, or by an army to strengthen a position. Such works are of three kinds, namely, those that are assailable only in front, those that are assailable in front and on the flanks, and those that are assailable on all sides.

Wiktionary

1. n. uncountable work done, or observations made out in the real world rather than in controlled conditions
2. n. countable A temporary fortification built by troops

GNU Webster's 1913

1. n. (Mil.) Any temporary fortification thrown up by an army in the field; -- commonly in the plural.

WordNet 3.0

1. n. an investigation carried out in the field rather than in a laboratory or headquarters
2. n. a temporary fortification built by troops in the field