What is the Greek word for forgotten one?

There isn't one single perfect Greek word for "forgotten one." Greek, like other languages, expresses this concept through phrases rather than a single word. However, you could use words and phrases to convey the meaning, depending on the nuance you want:

* λησμονημένος (lēsmōnēmenos): This is the past participle of the verb λήθομαι (lēthomai), meaning "to forget." It translates literally as "forgotten" and could be used to describe a person or thing. Adding a word like ἄνθρωπος (anthrōpos) for "person" would make it a forgotten *person*: λησμονημένος ἄνθρωπος (lēsmōnēmenos anthrōpos).

* ἀνεπιθύμητος (anepithūmētos): This means "unwanted" or "unremembered." It implies a lack of desire to remember, rather than simply a lapse in memory.

* ἐγκαταλελειμμένος (egkatalelimménos): This translates to "abandoned" or "forsaken," which often carries the connotation of being forgotten.

The best word or phrase to use would depend on the specific context. If you can provide more context about the situation or story where you want to use this word, a more precise translation can be offered.