The four stages of enlightenment

1. Arahant

"In this community of monks there are monks who are arahants, whose mental fermentations* are ended, who have reached fulfillment, done the task, laid down the burden, attained the true goal, totally destroyed the fetter of becoming (all ten fetters** are ended), and who are released through right gnosis...

2. Non-returner

"In this community of monks there are monks who, with the total ending of the five lower fetters, are due to be reborn [in the Pure Abodes], there to be totally unbound, never again to return from that world...

3. Once-returner

"In this community of monks there are monks who, with the total ending of [the first] three fetters, and with the attenuation of passion, aversion, & delusion, are once-returners, who — on returning only one more time to this world — will make an ending to stress...

4. Stream-winner

"In this community of monks there are monks who, with the total ending of [the first] three fetters, are stream-winners, steadfast, never again destined for states of woe, headed for self-awakening..."

— MN 118

*Fermentations-Pali word is 'asava' also sometimes translated "taints" or "fermentations."

**Fetters

The five lower fetters:

1. Self-identity views

2. Doubt (uncertainty)

3. Grasping at precepts & practices

4. Sensual desire

5. Ill will.

The five higher fetters:

1. Passion for form

2. Passion for what is formless

3. Conceit

4. Restlessness

5. Ignorance

Also read:Sarakaani Sutta-Sarakaani (Who Took to Drink)