From an unused root (meaning to move rapidly); freedom; hence, spontaneity of outflow, and so clear -- liberty, pure.
H1865. deror
I. דְּרוֺר noun [masculine] a flowing; free run, liberty; —
1 מָרדְּֿרוֺר Exodus 30:23 (P) i.e. myrrh of flowing, fine-flowing myrrh compare מֹר & Di.
2 with קרא proclaim liberty, לְכָליֿשְׁבֶ֑יהָ בָּאָרֶץ דְּרוֺר וּקְרָאתֶם Leviticus 25:10 (H) in Jubilee year, compare Isaiah 61:1 ("" מְּקַחקֿוֺחַ); Jeremiah 34:8, 15, 17 all reference to liberty of Sabbatical year; 34:17 (iron.) lo ! I proclaim to you liberty unto the sword, unto pestilence & unto famine, i.e. liberty to be destroyed by sword, pestilence and famine, (a judgment of Yahweh); ׳שְׁנַתהַֿדּ Ezekiel 46:17 i.e. year of Jubilee (cf Leviticus 25:10).