The kanji 保 can mean “to protect,” just as 守 does. I like when two kanji have the same meaning and then hook up in a compound.
Just as 保 can mean “to maintain unchanged,” so can 留 (RYŪ, to(maru): to keep in place, stay in a given condition). And, oh my goodness, now that I’ve seen the kun-yomi of to(maru) here, I realize that 留 has three to(maru) “cousins”:
留 (RYŪ, RU, to(maru): to keep in place, to stay in a given condition)
止 (CHI, to(maru): to stop)
停 (TEI, to(maru): to halt)Oh! This is the TEI of バス停 (basu tei: bus stop).
泊 (to(maru): to stay overnight)
All four to(maru) kanji also have the transitive form of to(meru).
If you turn your mind back to the first cousins (!) I mentioned, you realize that all six kanji have meanings related to stopping or keeping something as is. Yikes! Here are those two cousins again:
保 (HO, HŌ, tamo(tsu): to preserve, conserve, protect, keep)
守 (SHU, SU, mamo(ru): to protect)Anyway, all I meant to say (before things spun wildly out of control) is that 保 and 留 hook up in the following compounds, which are inverses:
留保 (ryūho suru: to reserve, withhold)
to keep for future use + to preserve
保留 (horyū: reserve, putting on hold, postponement, deferment) to preserve + to keep for future useWhile we’re at it, here are a few more combinations of the aforementioned cousins:
留守 (rusu: absence (from home), caretaking)
to stay + to protectYou may know this word from 留守番電話 (rusuban denwa: answering machine, to stay + to protect + guard + electricity + talk).
停止する (teishi suru: to stop, stand still, suspend, put to an end) to stop + to stop
Not too surprising a meaning, given the breakdown.
停留する (teiryū suru: to halt, stop) to halt + to stay
Hope I didn’t give you a headache with all this. Sometimes I think “disambiguation” (as they call it) is a useful exercise. Other times I think it just introduces anxiety that brings all kanji study to a 止/停.
