I. ˈwən adjective
Etymology: Middle English on, an, from Old English ān; akin to Old High German ein one, Latin unus (Old Latin oinos ), Sanskrit eka
Date: before 12th century
1. : being a single unit or thing
one day at a time
2.
a. : being one in particular
early one morning
b. : being preeminently what is indicated
one fine person
3.
a. : being the same in kind or quality
both of one species
b.
(1) : constituting a unified entity of two or more components
the combined elements form one substance
(2) : being in agreement or union
am one with you on this
4.
a. : some 1
will see you again one day
b. : being a certain individual specified by name
one John Doe made a speech
5. : only 2a
the one person she wanted to marry
II. noun
Date: before 12th century
1. — see number table
2. : the number denoting unity
3.
a. : the first in a set or series — often used with an attributive noun
day one
b. : an article of clothing of a size designated one
wears a one
4. : a single person or thing
has the one but needs the other
5. : a one-dollar bill
•
- at one
- for one
III. pronoun
Date: 13th century
1. : a certain indefinitely indicated person or thing
saw one of his friends
2.
a. : an individual of a vaguely indicated group : anyone at all
one never knows
b. — used as a third person substitute for a first person pronoun
I'd like to read more but one doesn't have the time
3. : a single instance of a specified action
felt like belting him one — John Casey
Usage:
Sense 2a is usually a sign of a formal style. A formal style excludes the participation of the reader or hearer; thus one is used where a less formal style might address the reader directly
for the consequences of such choices, one has only oneself to thank — Walker Gibson
This generic one has never been common in informal use in either British or American English, and people who start sentences with one often shift to another pronoun more natural to casual discourse
when one is learning the river, he is not allowed to do or think about anything else — Mark Twain
Use of one to replace a first-person pronoun—sense 2b—has occasionally been criticized. It is more common in British English than in American
I'm watching this pretty carefully and I hope that the issue will come up in the Lords and one may be able to speak about it — Donald Coggan