From the same root as tamar; a palm trunk -- palm tree.
see HEBREW tamar
H8560. tomer
תֹּ֫מֶר noun masculine palm-tree, post; — construct ׳ת דְּבוֺרָה Judges 4:5 palm-tree of Deborah; ׳כְּת מִקְשָׁה Jeremiah 10:5 like a post (i.e. a scare-crow; compare Baruch 6:70) in a cucumber field (simile of idol).