Great question! As I understand it, 'infectious' and 'affectionate' derived from Latin verbs with different endings, hence the inconsistencies. 'Inficere' (to taint, corrupt) gives us the basis for 'infect', while 'afficere' (to affect or influence) leads to 'affective' or 'affectionate'. Latin language rules are complex, but this is the gist! 👍

That's a good question man, I never noticed that before. Gonna stick around to see what answers you get, lol.

Because that's not how language works! 'Infectious' came directly from Latin, yes, but 'affectionate' came to us through a detour in Old French. Also, 'affectious' sounds weird. There, sorted.

Ja, why isn't it 'affectitious'? Or 'infectionary'? Get it together, English!

Complex question! The past participle stem of 'inficere' (to dye or poison) is 'infect-', thus 'infectious'. On the other hand, 'affectionate' comes from 'affectio', the noun form of 'afficere' (to have influence on). The '-ate' ending is common in forming adjectives off of verbs with '-io' endings. 'Affectious' would arguably be redundant due to the existence of 'affective' and 'effective'.

Uhh...I think it's the Latin roots? Like Infect comes from Inficere and I guess affection comes from Affectio? No idea about affectious though. 🤷

It's all about the roots, my man. 'Infect' is derived from the Latin word 'infectus' which is the past participle of 'inficere' meaning to stain, to dye. In contrast, 'affectionate' comes from 'affectio', from 'afficere', to influence. A different verb ending (-io instead of -us) gives us the '-ate' suffix. We don't have 'affectious' because the '-ious' suffix is typically added when an '-io' ending isn't present. Language is weird, but cool, isn't it?