Here you can find a few words the Baskar regularly use, if you want to pepper your posts with some of their language. These words are chiefly taken from the real-world Basque language; no offense meant to speakers thereof.
here is an online Basque translator for those who want words we don't have on this list. Note that certain words, like our words for 'chieftain', 'shaman', 'spirit,' some kinship terms, etc., are different from or adapted from the actual Basque.
Practical Words & Miscellaneous
food-- janari
bread-- ogi
cheese-- gazta
basket-- saski
farmer-- baserritar
peace-- bake
grain (usually barley)-- garia
tree-- zuhaitz
forest-- baso
meadow-- larre
bush-- sasi
gold-- urre
water-- ur
grape-- mahats
wine-- mahatsur
hello!-- aizu!
Winter-- Negu
Spring-- Udaberri
Summer-- Uda
Autumn-- Erori
Social & Kinship Terms
Warlord-- jaunko
chief-- jaun
warrior-- gudari
witch (the evil version of a shaman)-- sorgin
shaman (honorary son or daughter of a Spirit)-- sem'jainko or alab'jainko
father-- aita
husband-- emaita
daughter-- alaba
son-- seme
cousin-female-- lehengusina
cousin-male-- lehengusu
nephew, niece-- iloba
aunt-- izeba
mother-- ama
grandfather-- aitaita
grandmother-- amona
step-mother (and what a Warlord's children call wives who aren't their mother)-- ama-orde
widow-- alargun
wife-- emazte
brother-- anaia
sister of boy-- arreba
sister of girl-- ahizpa
twin (twins are considered very lucky and are honored)-- biki
the bond of marriage (as in, 'they were ezkondu' = 'they were married')-- ezkondu
concubine-- murroi-emazte
slave-- murroi
The Natural World & the Spirit World
There are animals, plants, etc. that can be used as your Endikai character's spirit animal. To say that your character is the spirit of _____, you say, jainko'____.ghost (spirit of the dead)-- mamu
spirit (of a tree, animal, etc., as in jainko'haritz, the spirit of the oak)-- jainko
Spirit World-- da'Jainko
bull-- zezen
cow-- behi
dog-- zakur
donkey-- asto
grasshopper-- matxin-salto
grass-- zelai
goat-- ahuntz
wolf-- otso
worm-- har
wind-- haize
river-- ibai
sky-- zeru
rain-- euri
fog-- laino
thunder-- trumoi
cloud-- lanbo
flame-- gar
ant-- inurri
horse-- zaldi
lion-- lehoi
bee-- erle
raven-- erroi
mackerel-- txitxarro
oak tree-- haritz
crab-- karramarro
cricket-- kilkir
ox-- idi
pig-- txerri
pigeon-- uso
rabbit-- untxi
ram-- aker
sheep-- ardi
snail-- marraskilo
snake-- suge
spider-- armiarma
star-- izar
swallow (the bird)-- enara
butterfly-- pinpilinpauxa
turtle-- dordoka
hawk-- aztore
falcon-- belatza
eagle-- arrano
Insults & Compliments
son or daughter of a dog (insult)-- sem'zakur or alab'zakur
son or daughter of a horse (a compliment)-- sem'zaldi or alab'zaldi
lazy (a dire insult)-- alfer
thief (also a dire insult; thieves are punished by lashing, sometimes fatally)-- lapur
lion (compliment meaning very brave, i.e. 'He was a true lehoi')-- lehoi