κεν (ken)
κεν is an Ancient Greek form of ἄν, meaning “modal particle: would, could; (with subj.) ever”. It is the particle.
Found 827 times in the Ancient Greek texts on Socratos.
Where it is used
Apollonius Rhodius, Argonautica 1.103: Πειρίθῳ ἑσπόμενον κοινὴν ὁδόν· ἦ τέ κεν ἄμφω
Euripides, Helen 590: λείψεις γὰρ ἡμᾶς, τὰ δὲ κένʼ ἐξάξεις λέχη;
Source: Socratos (socratos.org), a free reader for Ancient Greek and Latin. Grammar from the Perseus Treebank and Morpheus; dictionary entries from Liddell-Scott-Jones, A Greek-English Lexicon (Perseus Digital Library, CC BY-SA). Counts are from the texts on Socratos.