collider not found (java)

i have been making a game and it says collider not found and i dont know why. i tried UnityEngine.collider but other errors started showing up plz help i am a little bit new to java i only know a little bit but i cant find out what im doing wrong Plz help

Assets/Tower.js(53,40): BCE0018: The name ‘collider’ does not denote a valid type (‘not found’). Did you mean ‘UnityEngine.Collider’?

Case Matters! collider is not the same as Collider.

Also, Java is a programming language that is NOT used with Unity. You’re writing a variant of javascript. They are unfortunately named.

Here

#pragma strict

var myProjectile : GameObject;
var reLoadTime : float = 1f;
var turnSpeed : float = 5f;
var fireSpeed : float = .25f;
var muzzleEffect : GameObject;
var errorAmount ; float = .001f;
var myTarget : Transform;
var muzzlepositon : Transform[];
var turretBall : Transform;

private var nextFireTime : float;
private var nextMoveTime : float;
private var DesiredRotation : Quaternion;
private var aimError : float; 

function start() {

}

function Update() {

	if(myTarget) {
	
		if(Time.deltaTime >= nextMoveTime) {
		
			CalculateAimPositon(myTarget.position);
			turretBall.rotation = Quaternion.Lerp(turretBall.rotation, desiredRotation, Time.deltatime*TurnSpeed);
		
		}
	
		if(Time.time>= nextFireTime) {
		
		FireProjectile();
		
		}
	}
}


function OnTriggerEnter(other : collider) {

	if(other.GameObject.tag == "Enemy"){
	
		nextFireTime = Time.time+(reloadTime*.5);
		myTarget = other.GameObject.transform;
	
	}

}

function OnTriggerExit(other : collider) {

	if(other.GameObject.tag == myTarget){
	
		myTarget = null;

	}
}

function CalculateAimPosition(targetpos : Vector3) {

	var aimPoint = Vector3(targetpos.x+aimError, targetpos.y+aimError, targetpos.z+aimError);
	desiredRotation = Quaternion.LookRoration(aimPoint);
}

function CalculateAimError() {

	aimError = random.range[-errorAmount, errorAmount];

}

function FireProjectile() {

	audio.Play();
	nextFireTime = Time.deltaTime+reloadTime;
	nextMoveTime = Time.deltaTime+firePauseTime;
	CalculateAimError();



	for(theMuzzlePos in muzzlePosition) {
	
	
	Instantiate(myProjectile, theMuzzlePos.position, theMuzzlePos.rotation);
	Instantiate(muzzleEffect, theMuzzlePos.position, theMuzzlePos.rotation);
	
	}
}