specifa

There is no -if- suffix. The eye offers spec- + -if- + -a, and it is wrong twice over: Esperanto's make-something suffix is -ig- (beligi to beautify, plibonigi to improve), and there is no -if- in the affix system at all. Specifa is one borrowed root.

As with kuriero two ranks up, though, the false seam has a true seam behind it. The -fic- inside specificus really is Latin facere, to make, and the spec- really is species, which is also where speco comes from. So the analysis is correct history and incorrect grammar - and only the grammar is usable, because you cannot build new Esperanto words with a Latin suffix that Esperanto never adopted.

Specifa against speciala. They are not interchangeable, and English blurs them too.

• Speciala = special, singled out, given particular treatment. speciala oferto, a special offer.
• Specifa = specific, pinning down which exact one. specifa demando, a specific question.

A speciala amiko is a friend who matters more than the others. A specifa amiko is one particular friend, named. If you can substitute particular and keep the meaning, you want specifa; if you can substitute exceptional, you want speciala.

Related builds. Specifi is to specify, specifo a specification, and nespecifa non-specific.