rigidbody AddForce(transform.left) error

For some reason, whenever I try to run this code it says that transform does not have a definition for left. I have been looking at this code for ages and I still can’t see anything wrong with it. Here is the code.

using UnityEngine;
using System.Collections;

public class Bounce : MonoBehaviour {
	public float thrust;
	public Rigidbody rb;

	// Use this for initialization
	void Start () {
		rb = GetComponent<Rigidbody>();
		rb.AddForce(transform.left * thrust);
	// Update is called once per frame
	void FixedUpdate () {

Transform doesn’t have a left - I’m not sure how the error could have been more descriptive… Unity - Scripting API: Transform

Try -transform.right instead.