Strong's #3684: kciyl (pronounced kes-eel')
 from 3688; properly, fat, i.e. (figuratively) stupid or silly:--fool(-ish).
Brown-Driver-Briggs Hebrew Lexicon:
 ּ 
  kesı̂yl 
 
 1) fool, stupid fellow, dullard, simpleton, arrogant one
 
  Part of Speech: noun masculine
Relation: from H3688
Usage:
This word is used 70 times:
Proverbs 29:11: " A fool uttereth all his mind: but a wise it in till afterwards."
Proverbs 29:20: "that is hasty in his words? there is more hope  of a fool than of"
Ecclesiastes 2:14: "The wise man's eyes are in his head;  but the fool walketh and I myself perceived"
Ecclesiastes 2:15: "I in my heart, As it happeneth  to the fool, even to me; and why was I"
Ecclesiastes 2:16: "remembrance of the wise more than  of the fool forever; seeing that which now is in the days"
Ecclesiastes 2:16: "And how dieth the wise man? as  the fool."
Ecclesiastes 4:5: " The fool foldeth his hands together, and eateth his own flesh."
Ecclesiastes 4:13: "and a wise child than an old  and foolish king, who will"
Ecclesiastes 5:1: "to hear, than to give the sacrifice  of fools: for they consider not that"
Ecclesiastes 5:3: "cometh through the multitude of business;  and a fool's voice is known by multitude of words."
Ecclesiastes 5:4: "it; for he hath no pleasure  in fools: pay that which thou hast vowed."
Ecclesiastes 6:8: "hath the wise more than  the fool? what hath the poor, that knoweth to walk"
Ecclesiastes 7:4: "is in the house of mourning; but the heart  of fools is in the house of mirth."
Ecclesiastes 7:5: "than for a man the song  of fools."
Ecclesiastes 7:6: "a pot, is the laughter  of the fool: this also is vanity."
Ecclesiastes 7:9: "resteth in the bosom  of fools."
Ecclesiastes 9:17: "in quiet more than the cry  among fools."
Ecclesiastes 10:2: "A wise man's heart is at his right hand;  but a fool's heart"
Ecclesiastes 10:12: "mouth are gracious; but the lips  of a fool will swallow up"
Ecclesiastes 10:15: "The labor  of the foolish wearieth every one of them, because he knoweth how to go to"