The Collaborative International Dictionary of English v.0.48:

Client \Cli"ent\, n. [L. cliens, -emtis, for cluens, one who
   hears (in relation to his protector), a client, fr. L. cluere
   to be named or called; akin to Gr. ? to hear, Skr. [,c]ry,
   and E. loud: cf. F. client. See Loud.]
   1. (Rom. Antiq.) A citizen who put himself under the
      protection of a man of distinction and influence, who was
      called his patron.
      [1913 Webster]

   2. A dependent; one under the protection of another.
      [1913 Webster]

            I do think they are your friends and clients,
            And fearful to disturb you.           --B. Jonson.
      [1913 Webster]

   3. (Law) One who consults a legal adviser, or submits his
      cause to his management.
      [1913 Webster]

WordNet (r) 3.0 (2006):

client
    n 1: a person who seeks the advice of a lawyer
    2: someone who pays for goods or services [syn: customer,
       client]
    3: (computer science) any computer that is hooked up to a
       computer network [syn: node, client, guest]

The Free On-line Dictionary of Computing (30 December 2018):

client

    A computer system or process that requests a
   service of another computer system or process (a "server")
   using some kind of protocol and accepts the server's
   responses.  A client is part of a client-server software
   architecture.

   For example, a workstation requesting the contents of a file
   from a file server is a client of the file server.

   (1997-10-27)


Bouvier's Law Dictionary, Revised 6th Ed (1856):

CLIENT, practice. One who employs and retains an attorney or counsellor to
manage or defend a suit or action in which he is a party, or to advise him
about some legal matters.
     2. The duties of the client towards his counsel are, 1st. to give him a
written authority, 1 Ch. Pr. 19; 2. to disclose his case with perfect
candor3. to offer spontaneously, advances of money to his attorney; 2 Ch.
Pr. 27; 4. he should, at the end of the suit, promptly pay his attorney his
fees. Ib. His rights are, 1. to be diligently served in the management of
his business 2. to be informed of its progress and, 3. that his counsel
shall not disclose what has been professionally confided to him. See
Attorney at law; Confidential communication.