From the same as tsiyah in the sense of conspicuousness (compare natsach); a monumental or guiding pillar -- sign, title, waymark.
see HEBREW tsiyah
see HEBREW natsach
H6725. tsiyyun
צִיּוּן noun masculine sign-post, monument (Late Hebrew id. (צִיֵּין Pi`el denominative); probably from √ in original physical sense, see especially Arabic , Syriac , compare SchulthHom. Wurz. 57 Köii 1, 154; > √צין Buhl.); — absolute ׳צ, grave-stone 2 Kings 23:17; sign-post Ezekiel 39:15; guide-posts, plural צִיֻּנִים Jeremiah 31:21 ("" תַּמְרוּרִים).