Where does “irascendus” come from?

irascendus (Latin) comes from Latin īrāscor, from Latin īrātus, from Latin īra, from Latin eira, from Proto-Italic eisā, from Proto-Indo-European h₁eys- — to propel; to move quickly.

Definitions

Ancestry of “irascendus”, step by step

Step	Language	Word	Meaning
1	Latin	īrāscor	to be angry, to be enraged
2	Latin	īrātus	angry, irate, angered, enraged, furious, wrathful
3	Latin	īra	ire, anger, wrath
4	Latin	eira	—
5	Proto-Italic	eisā	—
6	Proto-Indo-European	h₁eys-	to propel; to move quickly

Every word from Proto-Indo-European h₁eys- →Every word from Proto-Italic eisā →Every word from Latin eira →