1. Μereerah ("bitterness".) Secreted in an animal's gall bladder. Poetically used for a vital part, Job 16:13; Job 20:25. Job 20:14, "the gall of asps," i.e. their poison, contained in a sac in the mouth; Scripture uses popular language when no moral truth is thereby endangered.
2. Rosh; a bitter and poisonous herb; the poppy (Gesenius). Rosh means "head", so we speak of poppy heads. Jeremiah 8:14, "water of gall," i.e. opium, Jeremiah 9:15; Jeremiah 23:15. Others suggest one of the Εuphorbiaceae , distasteful and deadly; the "grapes of gall" answering to the rounded three berried fruit (Imperial Bible Dictionary). Deuteronomy 29:18 (to which Hebrews 12:15, "root of bitterness," refers; a root whose essence is bitterness), Deuteronomy 32:32. Opium water would suit well for stupefying criminals in the agony of execution (Psalms 69:21; Matthew 27:34; Acts 8:23).
The vinegar offered to our Lord was mingled with "gall" according to Matthew, with "myrrh" according to Mark (Mark 15:23). The myrrh was the usual seasoning of Roman wine; the gall was added to stupefy, but our Lord would meet His agony in full consciousness. Bengel supposes the gall was added in wantonness. Matthew designated the drink according to the prophetic aspect, Psalms 69:21; Mark according to its outward appearance.