within

UK: /wɪˈðɪn/ US: /wɪðˈɪn, wɪθ-/ ,(wiᵺ in′, with-)

WordReference Random House Learner's Dictionary of American English © 2025

with•in /wɪðˈɪn, wɪθ-/   prep. 

1. in or into the interior of;
   inside:
   The noise came from within the house.
2. in the limits of;
   not beyond:
   to live within one's income.
3. in the field, sphere, or scope of:
   within the family; not within my power.

adv. 

4. in or into an interior or inner part:
   They proceeded within.
5. in the mind, heart, or soul;
   inwardly:
   listening to the voice within.

WordReference Random House Unabridged Dictionary of American English © 2025

with•in  (wiᵺ in′, with-), adv. 

1. in or into the interior or inner part;
   inside.
2. in or into a house, building, etc.;
   indoors:
   The fire was burning on the hearth within.
3. on, or as regards, the inside;
   internally.
4. inside an enclosed place, area, room, etc.:
   He was startled by a cry from within.
5. in the mind, heart, or soul;
   inwardly.

prep. 

6. in or into the interior of or the parts or space enclosed by:
   within city walls.
7. inside of;
   in.
8. in the compass or limits of;
   not beyond:
   within view; to live within one's income.
9. at or to some point not beyond, as in length or distance;
   not farther than:
   within a radius of a mile.
10. at or to some amount or degree not exceeding:
    within two degrees of freezing.
11. in the course or period of, as in time:
    within one's memory; within three minutes.
12. inside of the limits fixed or required by;
    not transgressing:
    within the law.
13. in the field, sphere, or scope of:
    within the family; within one's power.

n. 

14. the inside of a place, space, or building.

• Middle English withinne (preposition and adverb, adverbial), Old English withinnan (adverb, adverbial), equivalent. to with with- + innan from within, equivalent. to in in + -an suffix of motion from bef. 1000

Collins Concise English Dictionary © HarperCollins Publishers::

within / wɪˈðɪn/ preposition

1. in; inside; enclosed or encased by
2. before (a period of time) has elapsed: within a week
3. not beyond the limits of; not differing by more than (a specified amount) from: live within your means, within seconds of the world record

adverb

1. inside; internally