The Jesuit missionary Gabriel de Magalhães (1609-1677) gives one of the few early modern European accounts of the Dragon Boat Festival in his 1668 (but not published until 1688) account of the history of China. Magalhães refers to the festival as Lúm chuên, an obvious corruption of 龙船, but also mentions that the residents of Macao refer to the festival as Lumba Lumba: which I venture is derived from the Malay word for a ‘race’.
Relevant passages from the 1688 French and English editions:
Gabriel Magalhaens, New History of China, Containing a Description of the Most Considerable Particulare of that Vast Empire (London: Printed for Thomas Newborough, 1688), p. 107:
But in regard this Story is very like to that which occasion’d the Festival solemniz’d the fifth day of the fifth Moon, which the Inhabitants of Macao, if I am not deceiv’d, call Lumba Lumba, and the Chineses Lûm Chuen, that is to say Barks made in the form of a Dragon, wherein they sport themselves that day upon the Rivers [...].Gabriel de Magaillans, Nouvelle relation de la Chine, contenant la description des particularitez les plus considerables de ce grand empire (Paris: Claude Barbin, 1688), p. 131:
Mais comme cette Histoire ressemble fort à celle qui a esté cause de la Fête qu’on celebre le cinquiéme jour de la cinquiéme Lune, que ceux de Macao, sa je ne me trompe appellent Lumba Lumba, & les Chinois, Lúm chuên, c’est-à-dire, barques faites en forme de Dragon, dans lesquelles ils courent ce jour-là sur les rivieres [...]