IPA: /ˌsʌb.ɪnˈfjuː.deɪ.ʃən/
KK: /sʌbɪnˈfjuːdeɪʃən/
The act of a vassal leasing part of their feudal estate to another tenant, who then pays loyalty to the vassal.
The lord allowed for subinfeudation, enabling his vassals to lease portions of their land to others.
Subinfeudation is formed from "sub-" (meaning under) and "infeudare" (meaning to grant land in feudal tenure). The word refers to the process of granting land by a vassal to another vassal under the original lord's authority, thus creating a hierarchy of land ownership.
Think of 'sub-' meaning 'under' and 'infeudation' relating to land grants — this helps you remember that subinfeudation is about land being granted under another's authority.