Properly, passive participle of zaqen (used only in the plural as a noun); old age:-old age.
see HEBREW zaqen
H2208. zaqun
זְקֻנִים noun plural [masculine] old age — ׳בֶּןזֿ Genesis 37:3 i.e. a late-born son; ז ׳יֶלֶד 44:20 id.; לִזְקֻנָיו (ילדה)בֵּן 21:2, 7 (all J E).