Translation of "txeratsu" into English

Adibidez, txikitan uste nuen aitonak deitzen ninduen modu txeratsua -mozona- berak asmatutako hitz bat zela, berak zerabilela bakarrik, beste inorik ez munduan, eta ia nerabetan lehen aldiz joan nintzenean al pueblo, aitonaren errautsak eramatera hain zuzen, orduan jakin nuen harako hitz hura, inoiz berriz esango ez zidatela uste nuena, ez zela ondasun familiar pribatu bat.

For example, when I was little, I thought the affectionate term my grandfather used to address me—*mozona*—was a word he had invented himself, one that only he used—no one else in the world—and it was not until I visited the village as a near-teenager—specifically to take my grandfather’s ashes there—that I learned that word, which I thought I would never hear again, was not some private family possession.