All 9 Uses

phase
in
American Sniper
(Auto-generated)

Three phases follow: physical training, diving, land warfare.
p. 26.5 *

phases = stages (in the development of something)
When I was in, Hell Week came at the end of First Phase.†
p. 27.9
And then, before I knew it, First Phase started.†
p. 31.5
THE WEEK AFTER HELL WEEK IS A BRIEF RECOVERY phase called walk week.†
p. 39.6
I traded my white shirt for brown and began part two of BUD/S, the dive phase.†
p. 40.1
Not long after second phase started, I was in a dive tower, a special training apparatus that simulates a dive.†
p. 40.1
As soon as I was able, I helped the instructors, did daily PT, and ran with a class of white shirts (first phase) as they got their asses busted.†
p. 40.9
We came down, ready for the next phase—working in the city itself.†
p. 164.4
I worked with Marine snipers for several days during the first week or so of that phase of the assault.†
p. 165.1

Definitions:

(1) (phase as in: a critical phase)
a period of time or a stage during the development of something
(2) (phase as in: she's going through a phase)
a period of time when someone exhibits unusual behavior
(3) (phase as in: phased out over three years)
make a change gradually (phase in = gradually add; phase out = gradually removed)
(4) (meaning too rare to warrant focus)
More specialized and less common senses of the word are found in astronomy, physics, chemistry, and zoology. Consult a comprehensive dictionary if you wish to see those. All senses have to do with stages or periods of time.