Choose the perfect synonym or antonym for the word

Firstly

/ˈfɜːstli/

Used to introduce the first point or reason in a series.

Synonyms:

Firstly, wash your hands before cooking.Firstly, I’d like to thank everyone for coming.

Derived from the Middle English firsteliche, combining first with the adverbial suffix -ly, signifying the initial step or element.

58 mentions per 1 million words

Often

Hint: Frequency according to COCA