ὕσσωπος, -ου, ἡ [in LXX for אֵזוֹב ;] hyssop, of which a bunch was used in ritual sprinklings: Heb.9:19; of a branch or rod (?) of hyssop, Jhn.19:29 (but see Field, Notes, 106 ff., for suggestion to substitute ὑσσῷ here).† (AS)
Thayer:
1) hyssop 2) a plant used by the Hebrews in their ritual sprinklings
ὕσσωπος
hussōpos
hoos'-so-pos
Of foreign origin [H231]; “hyssop”