sign in

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Collins Concise English Dictionary © HarperCollins Publishers::

sign in vb (adverb)

to sign or cause to sign a register, as at a hotel, club, etc
to make or become a member, as of a club

sign /saɪn/USA pronunciation n. [countable]

an indication;
something that signifies something else:Bowing is a sign of respect.
a mark or symbol used as an abbreviation for the word or words it represents, as in music or mathematics, etc.:a dollar sign.
a gesture used to express or convey information, an idea, etc.:He raised his eyebrows, which was his sign that he didn't believe what I was saying.
a board, placard, etc., with writing or a drawing on it that bears a warning, advertisement, or other information for public view:a traffic sign.
something left behind that indicates the presence of something else;
a trace:There wasn't a sign of the crooks.
a signal or hint that something will happen;
an omen;
portent:The early frost was a sign of a long, harsh winter ahead.
Medicinean indication of a disease:Extra saliva at the mouth, odd behavior, and inability to drink are all signs of rabies.
Linguisticsany gesture that is a unit of meaning in sign language:She showed me the signs for "eat,'' "love,'' and "teacher.''
Astrologyone of the twelve signs of the zodiac:His sign is Capricorn; what's your sign?

to write (one's signature) on (something): [~ + object]to sign a letter.[no object]Where should I sign?
to hire by written agreement:[~ + object]to sign a basketball player.
to write one's signature to indicate acceptance, as of a contract for employment:[no object]refused to sign with the Yankees.
- to communicate by means of a sign;
  signal: [~ + object]He signed his obvious displeasure by frowning.[~ + that clause]He signed to her that they should leave.
- [no object] to make signals;
  communicate something by signals:She signed to the waiter for the check.
Linguisticsto convey or signal (a message) in a sign language: [no object]She signed frantically to him but he wasn't looking at her.[~ + object]She signed the words for "water'' and "glass'' to ask for a glass of water.
sign away or over, to dispose of by putting one's signature on a document: [~ + over + object]According to the agreement he has signed over all the property.[~ + object + over]She signed the property over to her daughter.
sign for, [~ + for + object] to sign one's name or signature to acknowledge that one has received (a package, letter, etc.):signed for the packages.
sign in (or out), [no object] to record one's arrival (or departure) by signing a register:He signed in when he got to work.
sign off, [no object]
- to stop broadcasting, esp. at the end of the day:The station signed off at three in the morning.
- to indicate one's approval openly if not formally:The boss signed off on my plan.
sign on:
- [~ + on + object] to hire:He signed on several good players.
- to agree to do something: [no object]He signed on as a pitcher for the team.[~ + on + to + verb]I signed on to help.
- [no object] to start a session with computer systems:He signed on to the system by typing his computer I.D. and his password.
sign up:
- [no object] to join an organization or group:to sign up for the navy.
- to hire: [~ + object + up]Sign him up if he can pitch tomorrow.[~ + up + object]to sign up some good players.

sign•er, n. [countable]See -sign-.

-sign-, root.

-sign- comes from Latin, where it has the meaning "sign;
have meaning.'' This meaning is found in such words as: assign, assignation, consign, cosign, design, designate, ensign, insignia, insignificant, resign, sign, signal, signature, signet, significant, signify, undersigned.

sign-in (sīn′in′),USA pronunciation n.

an act, an instance, or a time of signing in.

noun, nominal use of verb, verbal phrase sign in 1945–50

sign (sīn),USA pronunciation n.

a token;
indication.
Linguisticsany object, action, event, pattern, etc., that conveys a meaning.
a conventional or arbitrary mark, figure, or symbol used as an abbreviation for the word or words it represents.
a motion or gesture used to express or convey an idea, command, decision, etc.:Her nod was a sign that it was time to leave.
a notice, bearing a name, direction, warning, or advertisement, that is displayed or posted for public view:a traffic sign; a store sign.
a trace;
vestige:There wasn't a sign of them.
an arbitrary or conventional symbol used in musical notation to indicate tonality, tempo, etc.
Medicinethe objective indications of a disease.
Linguisticsany meaningful gestural unit belonging to a sign language.
an omen;
portent:a sign of approaching decadence.
AstrologySee sign of the zodiac.
LinguisticsSee sign language (def. 1).
Usually, signs. traces, as footprints, of a wild animal.
Mathematics
- Mathematicsa plus sign or minus sign used as a symbol for indicating addition or subtraction.
- a plus sign or minus sign used as a symbol for indicating the positive or negative value of a quantity, as an integer.
- See multiplication sign.
- See division sign.
- Mathematicsa symbol, as √ ̅ or !, used to indicate a radical or factorial operation.

v.t.

to affix a signature to:to sign a letter.
to write as a signature:to sign one's name.
to engage by written agreement:to sign a new player.
to mark with a sign, esp. the sign of the cross.
to communicate by means of a sign;
signal:He signed his wish to leave.
Linguisticsto convey (a message) in a sign language.
[Obs.]to direct or appoint by a sign.

v.i.

to write one's signature, as a token of agreement, obligation, receipt, etc.:to sign for a package.
to make a sign or signal:He signed to her to go away.
Linguisticsto employ a sign language for communication.
to obligate oneself by signature:He signed with another team for the next season.
sign away or over, to assign or dispose of by affixing one's signature to a document:She signed over her fortune to the church.
sign in (or out) to record or authorize one's arrival (or departure) by signing a register.
sign off:
- to withdraw, as from some responsibility or connection.
- to cease radio or television broadcasting, esp. at the end of the day.
- Informal Termsto become silent:He had exhausted conversation topics and signed off.
- to indicate one's approval explicitly if not formally:The president is expected to sign off on the new agreement.
sign on:
- to employ;
  hire.
- to bind oneself to work, as by signing a contract:He signed on as a pitcher with a major-league team.
- to start radio or television broadcasting, esp. at the beginning of the day.
- [Computers.]log¹ (def. 17a).
sign up, to enlist, as in an organization or group;
to register or subscribe:to sign up for the navy; to sign up for class.

Latin signāre to mark with a sign, inscribe, affix a seal to, derivative of signum
Old French signer
Latin signum mark, sign, ensign, signal, image; (verb, verbal) Middle English signen to mark with a sign, esp. the sign of the cross
Old French
(noun, nominal) Middle English signe 1175–1225