preposition / adverb
within
wih-THIN/wɪˈðɪn/
Inside the limits of something.
The child stands within the chalk circle while the toys remain outside.

Etymology
“Against the inside” places something on the inner side of a boundary. This spatial idea underlies the meaning of being inside the limits of something.
In context
on that cell phone that's always within arm's reach.
You had to work within specific height and width parameters.
More examples
- Please return the books within two weeks.
- We stayed within the marked boundary.
- A quiet voice came from within.
Forms
within
Similar words
- inside
- The common spatial alternative, less suited to some time limits.
- inside of
- A fuller expression, often more conversational.