Eureka (word)
"Eureka" comes from the Ancient Greek word "heúrēka", meaning "I found (it)", which is the first person singular perfect indicative active of the verb "heuriskō" "I find". It is closely related to heuristic, which refers to experience-based techniques for problem solving, learning, and discovery.
Aberri Eguna
"Aberri" is a neologism coined by Sabino Arana based on the suffix "-ba" which occurs in numerous kinship terms (e.g. "osaba" "uncle", "izeba" "aunt", "arreba" "sister of a man" etc.) from which he fancifully deduced a putative root *aba "father". He formed numerous neologisms based on this putative word such as "aberri" (*aba + "herri" "land, people, country, settlement"), "abizen" "surname" (*aba + "izen" "name") or "abenda" "race" (*aba + "enda" "lineage"). From "aberri" he then went on the coin "abertzale" "patriot" ("aberri" "fatherland" + "-(t)zale", a suffix denoting someone keen on something). In spite of their fanciful derivation, "aberri" and "abertzale" have found their way into general usage.