3one adjective
1 always used before a noun : having the value of 1
▪ There is one minute left in the game. ▪ I have a few one-dollar bills in my purse. ▪ She is one year old. 2 always used before a noun — used to refer to a single person or thing ▪ There is one cookie left. ▪ Let's take it one day at a time. [=let's not think or plan too far ahead] ▪ My one [=only, sole] concern is for your safety. ▪ We need to keep all the tools in one [=the same] place. ▪ He was the one (and only) person she wanted to marry. ▪ He caught the ball one-handed. ▪ a one-parent [=single-parent] family ▪ There is only/just one more thing to do. ▪ I could not solve one or two [=a few] problems on the test. ▪ Not one person knew the answer. [=no one knew the answer] 3 a — used before a noun to indicate that someone or something is part of a group of similar people or things ▪ She is one singer who I would like to see in concert. ▪ early one morning ▪ The Grand Canyon is one place I'd like to visit. ▪ That's one possible solution. ▪ I don't like being around him. For one thing, he smokes. ▪ The one thing I hate most is being lied to. ▪ It's one thing to understand the problem, but another thing to actually fix it.
b chiefly US, informal — used to emphasize a description ▪ She is one tough lady. [=she's a tough lady] ▪ That is one ugly dog. ▪ That was one great party. 4 always used before a noun : not known exactly : some
▪ I'll see you again one day soon. ▪ He'll come back one day. ▪ At one time or another/other, the building was a school. 5 — used to indicate that two or more people or things are actually the same person or are the same kind of thing ▪ The writer and her main character are one. ▪ “Puma” and “cougar” are different names for one animal. ▪ The writer and her main character are one and the same. 6 formal — used before a name to indicate that you do not know the person specified ▪ One Ms. Jones called this morning. [=a woman named Ms. Jones called this morning] 7 not used before a noun : in agreement with each other
▪ You and I are one on this issue.
▪ There is one minute left in the game. ▪ I have a few one-dollar bills in my purse. ▪ She is one year old.
b chiefly US, informal — used to emphasize a description ▪ She is one tough lady. [=she's a tough lady] ▪ That is one ugly dog. ▪ That was one great party.
▪ I'll see you again one day soon. ▪ He'll come back one day. ▪ At one time or another/other, the building was a school.
▪ You and I are one on this issue.
the one and only
— used before the name of a famous person to say that there is no one else like that person ▪ the one and only Elvis Presley
