Strong's #251: 'ach (pronounced awkh)
 a primitive word; a brother (used in the widest sense of literal relationship and metaphorical affinity or resemblance (like 1)):--another, brother(-ly); kindred, like, other. Compare also the proper names beginning with "Ah-" or "Ahi-".
Brown-Driver-Briggs Hebrew Lexicon:
 
  'âch 
 
 1) brother
 
 1a) brother of same parents
 1b) half-brother (same father)
 1c) relative, kinship, same tribe
 1d) each to the other (reciprocal relationship)
 1e) (figuratively) of resemblance
 
  Part of Speech: noun masculine
Relation: a primitive word
Usage:
This word is used 629 times:
Nehemiah 12:9: "Also Bakbukiah and Unni,  their brethren, them in the watches."
Nehemiah 12:24: "and Jeshua the son of Kadmiel,  with their brethren over against them, to praise and to give thanks, according to the commandment"
Nehemiah 12:36: " And his brethren, Shemaiah, and Azarael, Gilalai, Maai, Nethaneel, and Judah,"
Nehemiah 13:13: "they were counted faithful, and their office was to distribute  unto their brethren."
Esther 10:3: "among the Jews, and accepted of the multitude  of his brethren, seeking the wealth of his people, and speaking"
Job 1:13: "and drinking wine in their eldest  brother's house:"
Job 1:18: "and drinking wine in their eldest  brother's house:"
Job 6:15: " My brethren have dealt deceitfully as and as the stream of brooks they pass away;"
Job 19:13: "He hath put my brethren far  He hath put my brethren far from me, and mine acquaintance estranged from"
Job 22:6: "For thou hast taken a pledge  from thy brother and stripped the naked of their clothing."
Job 30:29: "I am  a brother to dragons, to owls."
Job 41:17: "They are joined one  to another, that they cannot be sundered."
Job 42:11: "Then came there unto him all  his brethren, and all his sisters, and all they that had been of his acquaintance"
Job 42:15: "gave them inheritance among  their brethren."
Psalms 22:22: "I will declare thy name  unto my brethren: of the congregation will I praise"
Psalms 35:14: "I behaved myself as though he had been my friend  or brother: heavily, as one that mourneth for his mother."
Psalms 49:7: "None of them can by any means redeem  his brother, nor give to God a ransom"
Psalms 50:20: "Thou sittest and speakest  against thy brother; thine own mother's son."
Psalms 69:8: "I am become a stranger  unto my brethren, unto my mother's children."
Psalms 122:8: "For  my brethren and companions' say, Peace"
Psalms 133:1: "good and how pleasant  it is for brethren to dwell together in unity!"
Proverbs 6:19: "and he that soweth discord among  brethren."
Proverbs 17:2: "and shall have part of the inheritance among  the brethren."
Proverbs 17:17: "loveth at all  and a brother is born for adversity."
Proverbs 18:9: "also that is slothful  is brother to him that is a great waster."
Proverbs 18:19: " A brother offended is harder to be won than a strong and their contentions are like the bars of a castle."
Proverbs 18:24: "a friend that sticketh closer than a brother.  than a brother."
Proverbs 19:7: "All  the brethren of the poor him: how much more do his friends go far"
Proverbs 27:10: "not; neither go  into thy brother's house in the day of thy calamity: for better"
Proverbs 27:10: "for better is a neighbor that is near than a brother  than a brother far off."
Ecclesiastes 4:8: "yea, he hath neither child  nor brother: yet is there no end of all his labor;"
Song of Solomon 8:1: "O that  thou wast as my brother, that sucked of my mother! when I should find thee without,"
Isaiah 3:6: "When a man shall take hold  of his brother of the house of his father, saying, Thou hast clothing, be"
Isaiah 9:19: "no man shall spare  his brother."
Isaiah 19:2: "against the Egyptians: every one  against his brother, and every one against his neighbor; city against city,"
Isaiah 41:6: "and every one said  to his brother, Be of good courage."
Isaiah 66:5: "at his word;  Your brethren that hated you, that cast you out for my name's sake,"
Isaiah 66:20: "And they shall bring all  your brethren for an offering unto the LORD out of all"
Jeremiah 7:15: "I have cast out all  your brethren, even the whole seed"
Jeremiah 9:4: "ye not in any  brother: for every brother"
Jeremiah 9:4: "any brother: for every  brother will utterly supplant, and every"
Jeremiah 12:6: "For even  thy brethren, of thy father, even they have dealt treacherously"
Jeremiah 13:14: "And I will dash them one against  another, even the fathers and the sons together, saith"
Jeremiah 22:18: "They shall not lament for him, saying, Ah  my brother! or, Ah sister! they shall not lament"
Jeremiah 23:35: "his neighbor, and every one to  his brother, What hath the LORD answered? and, What"
Jeremiah 25:26: "and near, one with  another, and all the kingdoms of the world, which"
Jeremiah 29:16: "that dwelleth in this city,  and of your brethren that are not gone forth with"
Jeremiah 31:34: "his neighbor, and every man  his brother, saying, Know the LORD:"
Jeremiah 34:9: "that none should serve himself of them, to wit, of a Jew  his brother."
Jeremiah 34:14: "years every man  his brother a Hebrew, which hath been sold"