If you don't like Wikipedia for your definitions, you could try any dictionary you are particularly fond of. The Wikipedia article also has a section about the person who first coined the term and what he meant by it, and a section about the Genocide Convention passed by the United Nations, if that would help.
Hamas is a resistance group. Their aim is the liberation of Palestine. IDF is a genocidal army, their aim is the eradication of Palestinians from the land of Palestine. One of these is doing anti-colonial resistance, the other is doing a genocide. Israel has stripped Palestinians of any political means of resistance, so the group naturally resorts to violence to achieve their goals (as horrible as that is). There is a big difference here. Israel is doing a genocide, Hamas is not.
And before you start accusing me of anti-semitism I am gonna be ahead of your game and remind you that your anti-academia stance rhymes a helluva lot with the cultural Marxism conspiracy theory, which is an actual anti-Semitic conspiracy theory, unlike credible accusations of genocide.
No, not accordinging to Wikipedia.
> Hamas is a resistance group.
No. Their aim is to slaughter Jewish people worldwide, which is in Hamas' founding charter.
> One of these is doing anti-colonial resistance
How? Arabs colonised the area in 650. Hamas openly chants that "from the river to the sea (ie, all of Israel), Palestine will be arab"
> Israel has stripped Palestinians of any political means of resistance,
Arabs can vote in Israel. Arabs cannot vote in Palestine.
> Israel is doing a genocide, Hamas is not.
Yes but why? Hamas deliberately eliminated, in part, Jewish people. That meets the definition you gave. Why is Hamas not committng genocide then?
> your anti-academia stance
I'm not anti academia. I'm just open about the biases of academia. It seems you are not.