living thing – any being that has the characteristics of life which includes all the following life processes: movement, respiration, sensitivity, growth, reproduction, excretion and nutrition

To remember the meaning of living thing, use the following mnemonic:

My living room was full of beings that have movement, respiration, sensitivity, growth, reproduction, excretion and nutrition. 

A living thing is an organism that carries out all seven life processes. These are movement, respiration, sensitivity, growth, reproduction, excretion and nutrition (often remembered as Mrs Gren). A living thing can be, amongst other things, a plant or an animal. 

Note: In biology respiration means using glucose to produce energy for muscles to move or for plants to grow.