Indo-European copula copula (with corresponding voiceless and voiced fricatives) existed side by side in Germanic, and the involvement of a separate root "" is unnecessary. The root "*(s)teh-" meant "to stand". From this root comes the present stem of the so-called "substantive verb" in Irish and Scottish Gaelic, "tá" and "tha" respectively. On the absence of the initial s- in Celtic, see Indo-European s-mobile. In Latin, "stō, stare" retained the meaning "to stand", until local forms of Vulgar Latin began to use it as a copula in certain circumstances. Today, this survives in that several Romance languages (Galician-Portuguese, Spanish, Catalan) use it
Indo-European ablaut Indo-European ablaut In linguistics, the Indo-European ablaut (pronounced ) is a system of apophony (regular vowel variations) in the Proto-Indo-European language. All modern Indo-European languages have inherited the feature, though its prevalence and productivity strongly varies. An example of ablaut in English is the strong verb "sing, sang, sung" and its related noun "song", a paradigm inherited directly from the Proto-Indo-European stage of the language. The term "ablaut" (from German "ab-" in the sense "down, reducing, gradated" + "Laut" "sound", thus literally meaning "sound gradation") was coined in the early nineteenth century by linguist Jacob Grimm. However, the phenomenon of