First & Firstly

First is an adjective and “firstly” is an adverb (and the same can be said for “secondly”, etc.).

Adverbs say something about a verb. Here is an example: Mr. Rajoy quickly ran into the bar.

That is easy. What about these sentences?

  • Firstly, Mr. Rajoy drank a beer.
  • Secondly, he drank a glass of red wine.

Where are the verbs that are attached to the adverbs (for example, firstly)? There are none. An error. The correct form should be:

  • First, Mr. Rajoy drank a beer. Second, he drank a glass of wine.

Words such as “first” are adjectives, in this case adjectives with elliptical (elíptico) nouns. The text could read: Mr. Rajoy´s first action was that he drank a beer. Here we have a sentence of ten words, compared to six words (First, Mr. Rajoy drank a beer).

On the basis that six words are better than ten words, we know which option to choose.