under zero angle of incidence

angle of incidence (optics)

angle of incidence

incidence of hot spots

incidence curve

zero-zero landing

zero-zero weather

zero degree angle

zero-lift angle

blind angle / dead angle

foot march under packs

hand-held under-barrel grenade launcher

restricted area (under military jurisdiction)

surveillance, under surveillance

under armor auxiliary power unit (UAAPU)

under arms

under barrel grenade launcher (UBGL)

under canvas

under command of

under cover of

under fire

under hatches

Under Secretary of Defense (USD)

Under Secretary of Defense for Acquisition, Technology, and Logistics (USD AT&L)

Under Secretary of Defense for Intelligence USD(I)

under-strength unit

under-vehicle improvised explosive device (UVIED)

nap-of-the-earth (NOE) (ground-hugging / terrain masking / flying under the radar / hedgehopping)

UBACS / Under Body Armour Combat Shirt

under nonnuclear conditions

under nuclear conditions

assume obligations under a treaty

office of the under secretary of defense for acquisition and technology