The Basque word for one is
bat

Translations for one and their definitions

bat	©
1. det. a, an, some
musu bat - a kiss
2. det. (after a numeral) some, about, around
Bidaiak hamar bat ordu iraungo du. - The trip will take around ten hours.
3. det. the same
4. num. number box, 1
5. num. one
Sagar bat eta lau laranja. - One apple and four oranges.
6. pron. some, something, someone