Choose the perfect synonym or antonym for the word

Firstly

/ˈfɜːstli/

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

Synonyms:

'It is only Firstly.Firstly, people generally don't like taking responsibility.Firstly, ensure that all documents are signed.

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