The following is a collection of attested nominal declensions in Gaulish, from Dictionnaire de la langue gauloise (2003) by X. Delamarre. It is important to review the attested evidence in order to observe their frequency, context, and other data, as well as to account for chronological and dialectal differences, and to compare against Proto-Celtic or other reconstructions. Also note that some sources (like the Larzac tablet) may have anomalous forms or some literary Latin influence that demands further study (e.g. bnanom).
Masculine: 1. -os > 2. (late) -o
Albanos (Grauf.), Andecamulos Toutissicnos (L-11), antumnos (Larzac), Arijos (L-12), Bratronos (L-6), Cantlos (Coligny), Cernunos (L-14), Crispos (L-16), Εβουρος (G-88), Iccanos (L-9), lekatos (E-5), Licnos Contextos (L-10, Rextugenos, Riuros (Coligny), Σεγομαρος, Siluanos, Tanotalos (E-1), Taruos (L-14), tuθos decametos (Grauf., Uabros (L-15) Ουμβρου-μαρος (G-27), Ουιλλονεος (G-153), etc.
Aneuno Oclicno (L-4), Peroco (L-7), ulano
Neuter: -on
brictom (Larzac), donicon (? Larzac), extincon (? Lezoux), meíon...ollon (Cham.), ]ramedon (L-16), reguccambion (Cham., acc. ?), tiopritom (Larzac)
Αδιατουσσια (G-107 b.), Adiega (Larzac), Adsagsona (Larzac), Buscilla (L-79), dona (Larzac), Ελουισσα (G-121), geneta, Μαγεσιλλα (G-193), Rufena Casta (Larzac), Seuera Tertionicna (Larzac), Ουενιτοουτα (G-106), etc.
Δαγο-λιτους (G-271), Esus (L-14), Λουγους (G-159), molatus (Lezoux), Trigaranus (L-14)
Masculine / Feminine: -is
autagis (Grauf.) Boudilatis (L-2), Koisis (E-5), Martialis (L-13), Ναμαυσατις (G-153), Τανχο-λατις (G-72)
Neuter: -e (-i)
brace, Condate, Briuate, broge, curmi, -rate
Masculine / Feminine: -u
Δολου (G-149), Κοννου (G-184), Frontu (L-3), Ουογιτιωυ (? G-251)
Neuter: -an
amman (? Coligny), garman (?), Menman-, toncnaman (Cham.)
duxtir, matir (Larzac)
Adiantunne (L-127), gnate (Lezoux), gnat' (Chât.), Papissone (Chât.)
Dagomotta, geneta, gnatha, Maternia (?), Taurina
ater (Chât.)
aruerriíatin (Cham.), ratin (L-3), Ucuetin (L-13), ]ατιν (G-212)
materem (Larzac)
ateknati trutikni (E-5), Cantli (Coligny), Dannotali (L-13), Equi (Coligny), Εσχεγγολατι (G-13), Gisaci (L-16), nepi (Larzac), Riuri (Coligny), Samoni (Coligny), Sauni (L-70), Segomari (L-133)
luxtos (Grauf.), gussou(s) (?Lezoux), nantou(s) (L-43), Penne-locos (NL)
andernados (Larzac), Ualentos (Larzac)
gussou (? Lezoux), Ταρανοου (G-27), Ουογιτωυ (?, G-251), ]σοου (?, G-212)
Κρειτε (G-213), luge (? Cham.), Ucuete (L-13)
Ατεμαγουτι (G-122), Epadatextorici (L-6), Μαγουρειγι (G-121)
βρατου ? (G-27, 28, 64, 66, 206, etc., doubtful, = more likely βρατου-), celicnu (dative ? L-51), Κομμου Εσχεγγιλου (G-154), sindiu (Coligny), sunartiu (Chamalières)
in Alixie (L-79), in dore core (Chât.), uo derce (? Larzac), in sinde (Larzac), suante (Chât.), teme uelle (? Chât.)
Masculine: 1. (archaic) -oi > then 2. -i
Neuter: -a
linda (L-50), onobia (L-51)
licuias, pannas (Grauf.)
Lugoues, cf. Co-medouis (Latin dat. pl.)
Masc.-Fem.: -is, -eis ?
Νιτιοβογεις (G-275), treis
Neuter: -ia
anatia (Larzac), peculia
Animate: -es
eurises (L-14), materes (Larzac), tidres (Grauf.)
Neuter: -a
anuana (Larzac)
catillus (Grauf.), mortarus (Grauf.) tuddus (Grauf.)
artuaš (E-5), billicotas rebellias (L-52), indas mnas ueronadas brictas (Larzac), caunonnas
anderon (Cham.), andedion (Cham.), batoron (Lezoux), dijuion (Cham.), neddamon (L-50), teuoxtonion (E-2)
bnanom (Larzac), eianon (eianom) (Larzac)
briuatiom (L-3)
Ματρον (Istre)
Rudiobo ?, aganntobo (L-15), corobo ? (Chât.)
Ανδοουναβο (G-83), Γλανειχαβο (G-64), Ναμαυσιχαβο (G-203), Ροχλοισιαβο (G-65), [Ου]λατιαβ[ο] (G-184)
atrebo (L-15), Ματρεβο (G-64, G-203)
Paullius (Larzac), τοουτιους (? G-153), Trigaranus (? L-14), Uindulus (? Grauf.)
anmanbe (Chât.), argant[—]ebi (Grauf.), banuabi (Negau), eiabi (Larzac), gandobe (Lezoux), gobedbi (L-13), mesamobi (Lezoux), suiorebe (L-6)