So, the WaniKani explanation for this vocab didn’t really stick with me. I thought about it for a while and came up with a way to explain it to myself. I just want to know if my thinking is flawed or if there is some better way to understand this.
WaniKani said that while おおきい means big, replacing the い with さ means size. So in my mind, it feels like adding the さ means the scale or thing your measuring.
For example, there’s the scale of small → big, but the overall scale would be size itself. Would this be accurate?
さ is a suffix that means something like “-ness”. In the case of 大きさ it would mean something like “bigness”, but size would sound more natural in English.
Or as Jisho puts it:
nominalizing suffix indicating degree or condition