Ufafanuzi wa kamusi ya "mamalia" ni mnyama mwenye uti wa mgongo mwenye damu joto wa tabaka linalotofautishwa na umiliki wa nywele au manyoya, utolewaji wa maziwa na majike kwa ajili ya lishe ya watoto wadogo, na (kawaida) kuzaliwa kwa vijana walio hai. Mamalia pia wana sifa ya mfumo wao wa juu wa neva, pamoja na ubongo uliokua vizuri, na idadi ya vipengele vingine kama vile mifupa mitatu ya sikio la kati na meno maalumu. Kundi la Mamalia linajumuisha aina mbalimbali za wanyama, kuanzia panya na panya hadi wanyama wakubwa zaidi duniani, kama vile nyangumi na tembo.
1. Every form of life that affected another, whether insect, bird, fish, or mammal, whether plant or particle, was a community of beings worthy of the deepest reverence.
2. Surfacing before him in the great Northwest Pacific was a school of orcas, farther off, watching the mammal they had learned never to trust.
3. It seemed unreal that the large mammal moved with such power and grace.