Strong's #3581: koach (pronounced ko'-akh)
 or (Dan. 11:6) kowach {ko'-akh}; from an unused root meaning to be firm; vigor, literally (force, in a good or a bad sense) or figuratively (capacity, means, produce); also (from its hardiness) a large lizard: -ability, able, chameleon, force, fruits, might, power(-ful), strength, substance, wealth.
Brown-Driver-Briggs Hebrew Lexicon:
 ּ / ּ 
  kôach 
 
 1) strength, power, might
 
 1a) human strength
 1b) strength (of angels)
 1c) power (of God)
 1d) strength (of animals)
 1e) strength, produce, wealth (of soil)
 
 2) a small reptile, probably a kind of lizard, which is unclean
 
 2a) perhaps an extinct animal, exact meaning is unknown
 
  Part of Speech: noun masculine
Relation: from an unused root meaning to be firm
Usage:
This word is used 126 times:
Genesis 4:12: "it shall not henceforth yield  unto thee her strength; a fugitive and a vagabond shalt thou be in the earth."
Genesis 31:6: "know that with all  my power I have served"
Genesis 49:3: "Reuben, thou art my firstborn,  my might, and the beginning of my strength, the excellency"
Exodus 9:16: "for to show in thee  my power; and that my name may be declared throughout all"
Exodus 15:6: "Thy right hand, O LORD, is become glorious  in power: thy right hand, O LORD, hath dashed in pieces"
Exodus 32:11: "out of the land of Egypt with great  power, and with a mighty hand?"
Leviticus 11:30: "And the ferret,  and the chameleon, and the lizard, and the snail, and the mole."
Leviticus 26:20: " And your strength shall be spent in vain: for your land shall not yield"
Numbers 14:13: "this people  in thy might from among"
Numbers 14:17: "And now, I beseech thee,  let the power of my Lord be great, according as thou hast spoken,"
Deuteronomy 4:37: "after in his sight with his mighty  power out of Egypt;"
Deuteronomy 8:17: "And thou say in thine heart,  My power and the might of mine hand hath gotten me"
Deuteronomy 8:18: "for it is he that giveth  thee power to get wealth, that he may establish"
Deuteronomy 9:29: "which thou broughtest out by thy mighty  power arm."
Joshua 14:11: "I was in the day that Moses sent  me: as my strength was then, even so is my strength now, for war,"
Joshua 14:11: "sent was then,  even so is my strength now, for war, both to go out, and to come in."
Joshua 17:17: "art a great people, and hast great  power: thou shalt not have one lot"
Judges 6:14: "him, and said, Go in this  thy might, Israel from the hand"
Judges 16:5: "him, and see his great  strength lieth, and by what means we may prevail against him, that we may bind him to afflict"
Judges 16:6: "me, I pray thee, wherein  strength lieth, and wherewith thou mightest be bound to afflict"
Judges 16:9: "is broken when it toucheth the fire.  So his strength was not known."
Judges 16:15: "told me wherein thy great  strength"
Judges 16:17: "womb: if I be shaven,  then my strength will go from me, and I shall become weak,"
Judges 16:19: "of his head; and she began to afflict  him, and his strength went from"
Judges 16:30: "with the Philistines. And he bowed  himself with all his might; and the house fell upon the lords,"
1 Samuel 2:9: "shall be silent in darkness; for  by strength shall no man prevail."
1 Samuel 28:20: "of Samuel: and there was no  strength in him; for he had eaten"
1 Samuel 28:22: "before thee; and eat, that thou mayest have  strength, when thou goest on thy way."
1 Samuel 30:4: "until they had no more  power to weep."
1 Kings 19:8: "and did eat and drink, and went  in the strength of that meat days"
2 Kings 17:36: "brought you up out of the land of Egypt  power and a stretched out"
2 Kings 19:3: "to the birth, and there is not  strength to bring forth."
1 Chronicles 26:8: "and their sons and their brethren, men  for strength for the service, were threescore and two"
1 Chronicles 29:2: "Now I have prepared with all  my might for the house of my God the gold for things to be made of gold,"
1 Chronicles 29:12: "thee, and thou reignest over all; and in thine hand  is power and might; and in thine hand it is to make great,"
1 Chronicles 29:14: "and what is my people, that we should be able  we should be able after this sort? for"
2 Chronicles 2:6: "But who is able  is able to build him a house, seeing the heaven and heaven"
2 Chronicles 13:20: "Neither did Jeroboam recover  strength again in the days of Abijah:"
2 Chronicles 14:11: "whether with many, or with them that have no  power: help us, O LORD our God; for"
2 Chronicles 20:6: "the kingdoms of the heathen? and in thine hand  is there not power and might, so that none is able to withstand"
2 Chronicles 20:12: "judge them? for we have no  might against great company"
2 Chronicles 22:9: "So the house of Ahaziah had no  power to keep still the kingdom."
2 Chronicles 25:8: "for God hath  power to help, and to cast down."
2 Chronicles 26:13: "hundred, that made war with mighty  power, to help the king against"
Ezra 2:69: "They gave  after their ability unto the treasure of the work threescore and one thousand drams"
Ezra 10:13: "and it is a time of much rain, and we are not  able without, neither is this a work"
Nehemiah 1:10: "whom thou hast redeemed by thy great  power, hand."
Nehemiah 4:10: "And Judah said,  The strength of the bearers of burdens is decayed, and there is much rubbish;"
Job 3:17: "cease from troubling; and there the weary  the weary be at rest."
Job 6:11: "What  is my strength, that I should hope? and what is mine end, that"