suggested that Lus was a form of the Celtic Lugus followed by another (unattested) root *tan-, supposed to mean "tribe",[3] while others derived the name from Lucis, an ancient people mentioned in Avienius' Ora Maritima (4th century AD) and from tan (-stan in Iranian), or from tain, meaning "a region" or implying "a country of waters", a root word that formerly meant a prince or sovereign governor of a region.

Luís de Camões' epic Os Lusíadas (1572), which portrays Lusus as the founder of Lusitania, extends these ideas, which have no connection with modern etymology.

[1] The archeologist Scarlat Lambrino defended the position that the Lusitanians were a tribal group of Celtic origin related to the Lusones (a tribe that inhabited the east of Iberia).

And yet the country north of the Tagus, Lusitania, is the greatest of the Iberian nations, and is the nation against which the Romans waged war for the longest timesThe Lusitani are mentioned for the first time in Livy who describes them as fighting for the Carthaginians in 218 BCE; they are reported as fighting against Rome in 194 BC, sometimes allied with Celtiberian tribes.

From 152 BC onwards, the Roman Republic had difficulties in recruiting soldiers for the wars in Hispania, deemed particularly brutal.

Two years after, in 137 BC Decimus Junius Brutus Callaicus led a successful campaign against the Lusitani, reaching as far north as the Minho river.

Five were Roman colonies:[12] Emerita Augusta (Mérida, Spain), Pax Iulia (Beja), Scalabis (Santarém), Norba Caesarina (Cáceres) and Metellinum (Medellín).

Prior to his invasion in 1807, Napoleon Bonaparte proposed the establishment of a French-backed puppet Kingdom of Northern Lusitania as one of the successor states to Portugal under the assumption that such a campaign would result in an easy French victory.

The province was also the namesake of the North Atlantic Ocean liner RMS Lusitania infamous for being torpedoed by a German U-boat in 1915.