Sii's answer is a good one.
To add a clarification, you asked:
Can a Japanese word combine both on'yomi and kun'yomi characters?
Japanese characters are neither on'yomi or kun'yomi. The characters are just graphical representations.
The words on'yomi and kun'yomi describe the readings for Japanese characters (specifically kanji). That's actually what the ...
I'm not sure about other Asian languages but this is how Japanese happens to be: a lot of kanjis have more than one reading (and meaning). How to find out the reading in each specific case? Well, bad news is that you'll have to memorize this. Sometimes it gets to be almost absurd. Check this out:
生 — nama — raw; uncooked; fresh
生 — sei — life; living
生 — ki ...
Yes, パンツ【HLL】 tends to refer to underwear, and パンツ【LHH】 tends to refer to trousers. パンツ in Japanese traditionally referred to only the former, and the latter is a relatively recent usage initially used in the apparel industry (cf. words borrowed twice). If I understand correctly, younger or fashion-conscious people tend to distinguish between these ...