Semen /ʂemen/ or Xemen /ʃemen/ is a medieval Basque given name of the Vasconic area. It is based on the Basque root seme < senbe 'son' as found in the ancient Aquitanian name Sembetten, attested form "sehi" as 'child', hypothetical ancient root *seni (cf. Koldo Mitxelena and modern form "senide" = 'brother or sister', 'relative'). The explanation by the Biblical name Šim’ōn (Simon) is less convincing.
Someone named "Seguin" was attested in Frankish chronicles when referring to the Count of Bordeaux and Duke of Vasconia (778, 814 and 816). The name is also recorded as Sihiminus, perhaps a misspelling of Ximinus, may have been a local Basque whose family later fled south over the Pyrenees and helped Enneco Arista take over in Pamplona.
Another character is identified in 778 as "Jimeno, the strong", from Arab sources in Al-Andalus, where it calls him "Mothmin al-Akra", a Basque or Hispanic magnate in the upper Ebro territories within the later independent principality of Navarre. This person was possibly related to others near Pamplona in local opposition to both the invading Franks under Charlemagne and the new ruler of the Islamic Iberian realm, Abd al-Rahman I.
Some think the name may be a corruption of the later part of the Latin name Ma-ximinus, as there is late Classic records that various individuals with this name were becoming very active as officials and residents in upper Hispania near the Pyrenees and Tarraconensis during the last century of the Western Roman Empire, and perhaps into the transition from imperial province to independent Kingdom during the Visigothic rule.
Other than these early medieval examples, it is widely known on both sides of the Pyrenees in the following forms:
Semen or Semeno fem. Semena
Semero fem. Semera
Scemeno (in Villabáscones)
Xemen or Xemeno fem. Xemena
Ximeno or Jimeno fem. Ximena or Jimena (French Chimène)
By adjunction of the suffix -ez, it produces the Iberian patronyms:
Portuguese: Ximenes [ʃiˈmeneʃ]
Spanish: Ximénez, Giménez, Jiménez [xiˈmeneθ]