Definite or indefinite form

[Nordic Bill]

Which would be the correct phrasing?:
The word “to” is both a conjunction and a sign of the infinitive; or
The word “to” is both a conjunction and a sign of an infinitive.
If anyone has a better option than either of these two, I'd really appreciate hearing it! (I am doubtful as to whether I replaced the wrong indefinite article with a definite one ) ...
Take care,
Bill

[Nordic Bill]

Sorry - I discovered almost immediately after posting this question that I seemed to have used some incorrect terminology. It would seem the correct term is "infinitive particle".
I assume therefore that the proper phrasing would be "The word “to” is both a conjunction and infinitive particle".
Thanks,
Bill

[Tdol]

People also use 'infinitive marker'. I would also add 'an/the' to balance the sentence.

[Nordic Bill]

Thanks tdol. I'll make a note of that alternate term.

Take care,
Bill

[Tdol]

Some people are not happy with the term 'particle', which they think is ill-defined, which is, I suppose, the reason for the alternative.

[Nordic Bill]

Thanks again, tdol. I have to admit, I never would have guessed this to be a particle, so for future reference I'll make sure I have both terms logged.
Rgs,
Bill

[Casiopea]

Bill, to functions as both a preposition and an infinitive marker, and, according to my Pocket Oxford, as an adverb in "so as to" (?).

[Nordic Bill]

Truly amazing - I completely overlooked that final possibility.
Thanks for the tip.
Bill