It's simply صَديق / صَديقَة to mean friend (2 or more people have a friendship relationship) but sometimes they translate the word "boyfriend" and "girlfriend" as صَديق / صَديقَة, because simply in Arabic there no equivalent for this term "boyfriend" and "girlfriend". So do not get confused about the translation, it's simply صَديق / صَديقَة. p.s : This is in MSA (Modern Standard Arabic), in dialects they change sometimes.

you can also say:رفيق او زميل

Yes, variations of the term depend on the region. but, you'll never be wrong if you use the word صديق. everybody will understand it as "friend".

صدیق (male friend= Sedigh) and صدیقه (female friend= sedigha) رفیق or رفیقه (include some other meanings)

Male friend: صَديق Female Friend:صَديقة