The Collaborative International Dictionary of English v.0.48:

Morse code \Morse" code"\ (Teleg.)
   a telegraphic code, in which dots, dashes, and spaces
   represent letters, numbers, and other elements of text. The
   original code was invented by Samuel B. Morse. The code now
   mostly used is the International Morse code, also referred
   to simply as the Morse code.
   [1913 Webster +PJC]

   Note: The present International Morse Code is given in the
         table below. There are no spaces in the International
         Morse Code.
         Alphabet
         --------------------------------------------------------
         A .- H .... O --- V ...
         B -... I .. P .--. W .
         C _._. J .--- Q --.- X -..
         D -.. K -.- R .-. Y -.
         E . L .-.. S ... Z --..
         F ..-. M -- T
         G --. N -. U ..
         Numerals
         1 .---- 4 ....- 7 --...
         2 ..--- 5 ..... 8 ---..
         3 ...-- 6 -.... 9 ----.
         0 ---
         Punctuation
         . (Period) .-.-.-, (Comma) --..
         ? (Question Mark) ..--..; (Semicolon) -.-.-. : (Colon)
         ---... ' (apostrophe) .----. - (hyphen) -....- /
         (forward slash) -..-. ( (left parenthesis) -.--. )
         (right parenthesis) -.--.-
         --------------------------------------------------------------
         The Alphabetic code which was originally in use in
         North America is given in the table below. In length,
         or duration, one dash is theoretically equal to three
         dots; the space between the elements of a letter is
         equal to one dot; the interval in spaced letters, as O
         . ., is equal to three dots. There are no spaces in any
         letter composed wholly or in part of dashes. Alphabet
         A .- H .... O . . V ...
         B - . . . I .. P ..... W .
         C .. . J -.-. Q ..-. X .-..
         D -.. K -.- R . .. Y .. ..
         E . L --- S ... Z ... .
         F .-. M -- T -- & . ...
         G --. N -. U ..
         Numerals
         1 .--. 4 . . . .- 7 --..
         2 ..-.. 5 --- 8 - . . . .
         3 . . . -. 6 . . . . . . 9 -..
         0 ---- Period ..--.. Comma .-.
         The Morse code was used chiefly with the electric
         telegraph, but is also employed in signalling with
         flags, lights, etc.
         [Webster 1913 Suppl. +PJC]

WordNet (r) 3.0 (2006):

Morse code
    n 1: a telegraph code in which letters and numbers are
         represented by strings of dots and dashes (short and long
         signals) [syn: Morse, Morse code, international Morse
         code]

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

Morse code

    A coding system invented by Samuel A. Morse,
   for use in sending character data over extremely low-quality
   pathways -- such as telegraphs and low-quality radio.  Morse
   code expresses characters as pulses of different durations.
   Short signals are called "dots" and long signals are calles
   "dashes".  The coding assigns shorter sequences to the most
   frequently used characters.

   American Morse code is the first and original Morse code
   character set.  Character sets adapted to other languages
   were developed later.

   American Morse Code:

    A . __        J . .          S . . .       1 . __ __ .
    B __ . . .    K __ . __      T __          2 . . __ . .
    C . .  .      L ___          U . . __      3 . . . __ .
    D __ . .      M __ __        V . . . __    4 . . . . __
    E .           N __ .         W . __ __     5 __ __ __
    F . __ .      O .  .         X . __ . .    6 . . . . . .
    G __ __ .     P . . . . .    Y . .  . .    7 __ __ . .
    H . . . .     Q . . __ .     Z . . .  .    8 __ . . . .
    I . .         R .  . .       0 ____        9 __ . . __

   Where . is a short pulse, __ a long pulse, ___ a very long
   pulse and ____ a extra long pulse.  There are also long and
   short spaces character-internal.  Intercharacter spaces are
   very long and interword spaces are extra long.  There is no
   standarisation in these durations, and they vary depending on
   the coder's preference and on the quality of the line.

   Continental Morse Code or International Morse Code is a widely
   used de-facto standard.  This table summarises the Western
   European usage of Continental Morse Code:

     A .-    G --.    M --    S ...   Y -.--   4 ....-
     B -...  H ....   N -.    T -     Z --..   5 .....
     C -.-.  I ..     O ---   U ..-   0 -----  6 -....
     D -..   J .---   P .--.  V ...-  1 .----  7 --...
     E .     K -.-    Q --.-  W .--   2 ..---  8 ---..
     F ..-.  L .-..   R .-.   X -..-  3 ...--  9 ----.

     A-umlaut (1)  .-.-      E-acute       ..-..
     A-acute       .--.-     N-tilde       --.--
     A-corona (11) .--.-     O-umlaut (1)  ---.
     CH (2)        ----      U-umlaut (1)  ..--

     Punctuation Marks:            Other Signs:

     period              .-.-.-    warning                      .-..-
     comma               --..--    error                        ........
     question mark       ..--..    repetition (ii ii)           .. ..
     hyphen              -....-    wait (AS)                    .-...
     colon (3)           ---...    interruption (BK)            -...-.-
     underline (4)       ..--.-    understood (VE)              ...-.
     apostrophe          .----.    transmission received (R)    .-.
     quotation mark      .-..-.    beginning of message (KA)    -.-.-
     parenthesis open (5)-.--.     end of message (AR)          .-.-.
     parenthesis (close) -.--.-    end of transmission (K) (6)  -.-
     equal sign (7)      -...-     end of transmission (KN) (8) -.--.
     plus sign           .-.-.     closing mark (SK) (9)        ...-.-
     multiplication sign -..-      closing station (CL)         -.-..-.
     fraction mark       -..-.
     separator (10)     .-..-

     (1) Note: 'umlaut' is also known as 'diaeresis'
     (2) Used only in German; not in Dutch.
     (3) also: 'divided by'
     (4) before and after the word to be underlined
     (5) purportedly replaced by -.--.- for both "(" and ")"
     (6) both and invitation to any station to start transmission
     (7) also used as spacing between parts of transmission
     (8) also an invitation to one station in particular to start
         transmission
     (9) connection will be closed.
     (10) in fractions, for example.
     (11) A-ring ?

   Where '.' is a short pulse, '-' a long one.  A '-' is three
   times as long as a '.'; character-internal spaces are as long
   as '.'s.  Intercharacter space are as long as -'s.  Spaces
   between words are as long as seven '.'s.

   (1996-11-23)