an echoic word, the referent of which is a tone interval approximately three times the length of the dot, used to designate the dash of Morse code, International Morse code, etc.
Likewise, continuous dahs are created by holding the dah contact.
Do dah day is an annual pet parade held around the end of may.
British Dictionary definitions for dah
dah
/dɑː/
noun
1.
the long sound used in combination with the short sound dit, in the spoken representation of Morse and other telegraphic codes Compare dash1 (sense 14)