"person who is responsible for the property of another," 1640s, from trust (v.) + -ee.
Entries linking to trustee
trust v.
c. 1200, from Old Norse treysta "to trust, rely on, make strong and safe," from traust (see trust (n.)). Related: Trusted; trusting.
-ee
word-forming element in legal English (and in imitation of it), representing the Anglo-French -é ending of past participles used as nouns (compare -y (3)). As these sometimes were coupled with agent nouns in -or, the two suffixes came to be used as a pair to denote the initiator and the recipient of an action.
Not to be confused with the French -ée that is a feminine noun ending (as in fiancée), which is from Latin -ata.
trusteeship n.
1730; see trustee + -ship.
Such a word as trusteeship is eminently characteristic of the composite character of the language: Scandinavian trust + a French ending used in a manner unparalleled in French + an Old English ending. [Otto Jespersen, "Growth and Structure of the English Language"]