premièrement bedeutet auf Englisch

firstly▼◼◼◼(in the first place)
adverb
[UK: ˈfɜːst.li] [US: ˈfɝːst.li]

first▼(before anything else)
adverb
[UK: ˈfɜːst] [US: ˈfɝːst]

for one thing▼◼◻◻((to introduce the first item))
preposition
[UK: fɔː(r) wʌn ˈθɪŋ] [US: ˈfɔːr wʌn ˈθɪŋ]