All 7 Uses

focus
in
The Martian
(Edited)

Yesterday, at our request, the entire SETI network focused on Mars.
p. 61.9

focused = pointed
I can't promise we'll succeed in rescuing him, but I can promise this: The entire focus of NASA will be to bring Mark Watney home.
p. 62.5 *

focus = place where attention is directed
"Focus, Jack," interrupted Venkat.
p. 121.6

focus = concentrate
Focus on the task at hand.
p. 134.8 *
Our focus is food.
p. 174.1

focus = where attention is concentrated
From now on, your only focus is examining imagery of Ares 3.
p. 271.4

focus = place where attention is directed
So today was focused on getting the rover righted.
p. 315.6

focused = concentrated

Definitions:

(1) (focus as in: Turn your focus to question #2.)
to direct attention or effort toward a single thing; or the ability to do so without getting distracted
(2) (focus as in: The focus of our study is...)
where attention is concentrated or directed
(3) (focus as in: bring into focus; or out of focus)
a state where something has come into view or can be seen clearly; or an adjustment made to permit a clear view
(4) (focus as with technical usage)
technical usage typically involves some sense of center or concentration such as:
- physics — a point where things come together such as the point where light rays meet
- geometry — a fixed reference point (as of a parabola)
- geology — the point of origin of an earthquake
See a comprehensive dictionary for other less common meanings.
(5) (meaning too rare to warrant focus)