Strong's #389: 'ak (pronounced ak)
 akin to 403; a particle of affirmation, surely; hence (by limitation) only:--also, in any wise, at least, but, certainly, even, howbeit, nevertheless, notwithstanding, only, save, surely, of a surety, truly, verily, + wherefore, yet (but).
Brown-Driver-Briggs Hebrew Lexicon:
 
  'ak 
 
 1) indeed, surely (emphatic)
 2) howbeit, only, but, yet (restrictive)
 
  Part of Speech: adverb 
Relation: akin to H403
Usage:
This word is used 160 times:
Judges 20:39: "persons: for they said,  Surely they are smitten down before"
1 Samuel 1:23: "tarry until thou have weaned  him; only the LORD establish his word."
1 Samuel 8:9: "Now therefore hearken unto their voice:  howbeit yet protest solemnly unto them, and show"
1 Samuel 12:20: "all this wickedness:  yet turn not aside from following"
1 Samuel 12:24: " Only fear the LORD, and serve him in truth with all your heart:"
1 Samuel 16:6: "Eliab, and said,  Surely the LORD's anointed is before"
1 Samuel 18:8: "ten thousands, and to me they have ascribed but thousands: and what can he have more  but the kingdom?"
1 Samuel 18:17: "Merab, her will I give thee to wife:  only be thou valiant for me, and fight"
1 Samuel 20:39: "knew not any thing:  only Jonathan and David knew"
1 Samuel 21:4: "hallowed bread; if the young men have kept themselves  at least from women."
1 Samuel 25:21: "Now David had said,  Surely in vain have I kept all that"
1 Samuel 29:9: "in my sight, as an angel of God:  notwithstanding the princes of the Philistines have said, He shall not"
2 Samuel 2:10: "and reigned two years.  But the house of Judah followed"
2 Samuel 3:13: "will make a league with  thee: but one thing I require"
2 Samuel 23:10: "day; and the people returned after  him only to spoil."
1 Kings 9:24: " But Pharaoh's daughter came up out of the city of David unto"
1 Kings 11:12: " Notwithstanding in thy days I will not do it for David thy father's sake: but I will rend"
1 Kings 11:39: "the seed of David,  but not forever."
1 Kings 17:13: "go and do as thou hast said:  but make me thereof a little"
1 Kings 22:32: "Jehoshaphat, that they said,  Surely it is the king of Israel. And they turned aside"
1 Kings 22:43: "it, doing that which was right in the eyes of the LORD:  nevertheless the high places were not taken away;"
2 Kings 5:7: "me to recover a man of his leprosy?  wherefore consider, I pray you,"
2 Kings 12:13: " Howbeit there were not made for the house of the LORD bowls of silver, snuffers,"
2 Kings 13:6: " Nevertheless they departed not from the sins of the house of Jeroboam, who"
2 Kings 18:20: "Thou sayest,  (but they are but vain words,) I have counsel and strength for the war. Now"
2 Kings 22:7: " Howbeit there was no reckoning made with them of the money that was delivered into their hand,"
2 Kings 23:9: " Nevertheless the priests of the high places came not up to the altar of the LORD"
2 Kings 23:26: " Notwithstanding the LORD turned not from the fierceness of his great wrath,"
2 Kings 23:35: "the silver and the gold to Pharaoh;  but he taxed the land to give"
2 Kings 24:3: " Surely at the commandment of the LORD came this upon Judah, to remove them out of"
1 Chronicles 22:12: " Only the LORD give thee wisdom and understanding, and give thee charge concerning Israel,"
2 Chronicles 20:33: " Howbeit the high places were not taken away: for as yet the people had not prepared"
2 Chronicles 30:11: " Nevertheless divers of Asher and Manasseh and of Zebulun humbled themselves,"
Ezra 10:15: " Only Jonathan the son of Asahel and Jahaziah the son of Tikvah were employed"
Job 2:6: "Satan, Behold, he is in thine hand;  but save his life."
Job 13:15: "Though he slay me, yet will I trust  in him: but I will maintain mine own ways before"
Job 13:20: " Only do not two things unto me: then will I not hide myself"
Job 14:22: " But his flesh upon him shall have pain, and his soul within him shall mourn."
Job 16:7: " But now he hath made me weary: thou hast made desolate all my company."
Job 18:21: " Surely such are the dwellings of the wicked, and this is the place of him that knoweth not"
Job 19:13: "He hath put my brethren far from me, and mine acquaintance  are verily estranged from"
Job 23:6: "me with his great power? No;  but he would put"
Job 30:24: " Howbeit he will not stretch out his hand to the grave, though they cry in his destruction."
Job 33:8: " Surely thou hast spoken in mine hearing, and I have heard the voice of thy words,"
Job 35:13: " Surely God will not hear vanity, neither will the Almighty regard"
Psalms 23:6: " Surely goodness and mercy shall follow me all the days of my life: and I will dwell"
Psalms 37:8: "from anger, and forsake wrath: fret not thyself  in any wise to do evil."
Psalms 39:5: "and mine age is as nothing before  thee: verily every man at his best state is altogether"
Psalms 39:6: " Surely every man walketh in a vain show: surely they are disquieted in vain: he heapeth up"
Psalms 39:6: "every man walketh in a vain show:  surely they are disquieted in vain: he heapeth up riches, and knoweth"