Definition (full): oh that!, with leave, if it please
Strong's Exhaustive Concordance
Perhaps from ba'ah (in the sense of asking); properly, a request; used only adverbially (always with "my Lord"); Oh that!; with leave, or if it please -- alas, O, oh.
KJV: Then Judah came near unto him, and said, Oh my lord, let thy servant, I pray thee, speak a word in my lord's ears, and let not thine anger burn against thy servant: for thou art even as Pharaoh.
NASB: Then Judah approached him, and said, "Oh my lord, may your servant please speak a word in my lord's ears, and do not be angry with your servant; for you are equal to Pharaoh.
KJV: And Moses said unto the LORD, O my Lord, I am not eloquent, neither heretofore, nor since thou hast spoken unto thy servant: but I am slow of speech, and of a slow tongue.
NASB: Then Moses said to the LORD, "Please, Lord, I have never been eloquent, neither recently nor in time past, nor since You have spoken to Your servant; for I am slow of speech and slow of tongue."