Adbertos (Gaulish) - An offering or ritual in which something is given to the Deuoi.

Andumnos (Gaulish) - The Underworld / Otherworld / Netherworld which corresponds to the Greek Elysian Fields and Tartaros, and to the Teutonic Valhall and Hel.  There are many isles of the Celtic Otherworld.  Andumnos was later called Annwn in Welsh, and Andomhain in Early Irish (Gaelic).

Ategenos (ah-the-gen-awss) - Rebirth; an incarnation or manifestation of a trait, talent, concept, spirit or divinity into human form.  It is usually genetically passed down.

Bardos, plural bardoi (Gaulish, Brittonic, Goidelic) - The old Celtic term for a singer or minstrel who sang praises of great heroes and chieftains, or satires (curses and insults).

Brehon (from Irish breithamhain) - A medieval Irish judge or jurist; a specialist of the old Druidic class that survived Christianization.

Celt (pronounced Kelt) - The ethnic group ancestral to the Irish, Scottish, Welsh, Cornish (of Cornwall), Breton, and Manx, and a high percentage of the French, Belgian and Swiss people.  Celtic (pronounced either Kel-tik or Sel-tik) and Celtophile are derivatives of this word.

CúChullain (koo-khullin) - The great epic hero of old Ulster stories such as the "Cattle Raid of Cooley."  He was the incarnation or manifestation of the Celtic high god of Lugus (Lugh or Llew).

Druidiactos (also Druidiaxtos)The Celtic religious movement returning to the traditional pre-Christian values, customs and faith of the Celtic people.

Filí (fee-lyeh) - A poet-magician or seer who performed Celtic magic and mystical rites.  The fili was a solitary practitioner, something like a shaman in other cultures.

Finn Mac Cumhail (fin mok kool) - The great hero and incarnation of Uindos (or Cernunnos, in Greek), son of Noudons in a group of great epic tales and romances called the Fenian cycle.

Geis or Geas (gayss), plural geassa (gassa) - A controlling spell or enchantment in which a certain action or behavior will cause another certain action or effect.  Usually it takes the form of a taboo or a destiny, as when CuChullain overheard Cathbad say that any boy who accepts weapons on that day would be destined to be a great hero, and he asked his king for arms.

Lebor (l’yower) - Old Irish word for book.

Noudons (now-dawns) - The Celtic god who represented the old retired king, a wizard and mystical grandfatherly figure. He was the blemished king, a wild-old-man god and a law-giver.  He was called Nuada Airgetlamh (noo-uh Arriget-louw) in Old Irish, Hudd (Neethe) or Llud Laww Ereint (hleethe hlouw air-eint) in Welsh.

Ogam (oh-um) - The notches and lines carved on sticks and stones by the Irish filidh and other learned folk.

P-Celtic - The Gaulish-Brittonic language from which Cornish, Breton and Welsh descend.

Q-Celtic - The Goidelic or ancient Gaelic language from which Old Irish evolved and developed into Middle Irish, and then ModernIrish, Gaelic (Scots Gaelic) and Manx Gaelic.  Irish calls "four" and "five" ceathair and cuig (ka-her and koo-eeg), Scots Gaelic calls them ceithair and coig (keh-her and koyk).

Sidhe (shee) - "Peace" in Old Irish.  Aes Sidhe, "or people of peace," is the name for the spirits and ghosts of the Otherworld.

Touta (toh-oo-tah) - A tribe or kindred of people who come together regularly.  They form a local community.  A congregation of people who meet regularly on a monthly basis, or at least four times a year to celebrate Celtic festivals.

UerDruis (also Verdruis) - The leader of the Celtic religious movement.