The pope, either alone or in communion with the bishops, may declare a teaching on faith or morals as infallible. This teaching is such, AND was confirmed in the subsequent answer to a dubia or doubt, by the CDF. (BTW, the word "infallible" does NOT have to appear in the teaching.) "Definitively held" does the same purpose.

By you not accepting it does not void this teaching. It is only your opinion.