English display and Spanish desplegar are cognates, but we can more easily understand the etymology of the Spanish verb. It comes from Medieval Latin displicāre, which changed the meaning of the classical Latin verb displicāre ‘to scatter,‘ a compound of dis- ‘apart’ and plicāre ‘to fold.’ The Medieval sense of displicāre, and hence desplegar, was ‘to unfold.’ English display has nothing to do with play, of course, but comes via Anglo-Norman despleier from the same Medieval Spanish displicāre that gave rise to desplegar. The modern Spanish verb has various senses: ‘to unfold, spread, open, display, expand, unfurl’ and, in a military sense, ‘to deploy.’ If English deploy looks suspiciously like display, it’s not a coincidence. Deploy goes back to Old French despleier, which evolved directly from classical Latin displicāre. As a result, English deploy and display are doublets, with the first coming from mainstream French and the second from Anglo-Norman.
© 2014 Steven Schwartzman