Gohan can be used to either mean lunch or dinner.
When a mother calls her family to the table in Japan, she says, "Gohan da yo", meaning, "It's meal time".

Gohan can also mean rice, but the implication here is that the rice is cooked. Uncooked rice is known as "kome".

I can't help wondering is it is a co-incidence that someone would ask about this one word, but anyway. If you know what I am talking about, yeah it means rice but it is also a joke. The "han" part is the part that means rice and the "go" is an honerific attached to it (hence it can be mean rice or meal). However, obviously with Go-kou, they are using a different "go", the Go from his name which means enlightnement, and then the same "han". So it is a play on the Kanji for Gokou's name as well. In this case, it was pretty much a one shot joke at the start of DB, for the name of Gokou's "grandfather", and then Gokou decided to call his son the same name. And so there you have.

If this was not related to DB then sorry, and I am sure you have no idea what I am talking about ^-^ enjoy