Unknown. None of the proposed etymologies is plausible (compare Ancient Greek ταχύς (takhús, “fast”), Icelandic tækur (“acceptable”).
Matasovic writes that it could possibly be assimilated from *dako-, which could be from Proto-Indo-European *dko-, also the source of *dekos- (“honor”). This root also gives Old Irish dech, the suppletive superlative to maith (“good”).
*dagos
O/ā-stem | |||
---|---|---|---|
masculine | singular | dual | plural |
nominative | *dagos | *dagou | *dagoi |
vocative | *dage | *dagou | *dagoi |
accusative | *dagom | *dagou | *dagons |
genitive | *dagī | *dagous | *dagom |
dative | *dagūi | *dagobom | *dagobos |
instrumental | *dagū | *dagobim | *dagobis |
feminine | singular | dual | plural |
nominative | *dagā | *dagai | *dagās |
vocative | *dagā | *dagai | *dagās |
accusative | *dagam | *dagai | *dagans |
genitive | *dagās | *dagous | *dagom |
dative | *dagai | *dagābom | *dagābos |
instrumental | *? | *dagābim | *dagābis |
neuter | singular | dual | plural |
nominative | *dagom | *dagou | *dagā |
vocative | *dagom | *dagou | *dagā |
accusative | *dagom | *dagou | *dagā |
genitive | *dagī | *dagous | *dagom |
dative | *dagūi | *dagobom | *dagobos |
instrumental | *dagū | *dagobim | *dagobis |
Declension of the comparative | |||
---|---|---|---|
masculine | singular | dual | plural |
nominative | *dagyūs | *? | *dagyoses |
vocative | *dagyūs | *? | *dagyoses |
accusative | *dagyosam | *? | *dagyosans |
genitive | *dagisos | *? | *dagisom |
dative | *dagisei | *? | *dagisbos |
instrumental | *dagisī | *? | *dagisbis |
feminine | singular | dual | plural |
nominative | *dagyūs | *? | *dagyoses |
vocative | *dagyūs | *? | *dagyoses |
accusative | *dagyosam | *? | *dagyosans |
genitive | *dagisos | *? | *dagisom |
dative | *dagisei | *? | *dagisbos |
instrumental | *dagisī | *? | *dagisbis |
neuter | singular | dual | plural |
nominative | *dagis | *? | *? |
vocative | *dagis | *? | *? |
accusative | *dagis | *? | *? |
genitive | *dagisos | *? | *dagisom |
dative | *dagisei | *? | *dagisbos |
instrumental | *dagisī | *? | *dagisbis |