The term 'TELEGRAPHY PIONEER' can be solved by the crossword solution 'MORSE' (5 letters). Samuel MORSE was an American inventor and painter who developed the single-wire telegraph system in the early 1840s. He is credited with inventing the MORSE code, a system of dots and dashes that represent letters and numbers, which was used to send messages over long distances. MORSE's invention revolutionized communication and laid the groundwork for modern telecommunications.