Ground substance is the background material within which all other connective tissue elements are embedded. In ordinary connective tissue, the ground substance consists mainly of water whose major role is to provide a route for communication and transport (by diffusion) between tissues.
Definitions for tiredness. Here are all the possible meanings and translations of the word tiredness. Princeton's WordNet(0.00 / 0 votes)Rate this definition: fatigue, weariness, tiredness(noun) temporary loss of strength and energy resulting from hard physical or mental work. he was hospitalized for extreme fatigue; growing fatigue was apparent from the decline in the execution of their athletic skills; weariness overcame her after twelve hours and she fell asleep.
Fatigue is a subjective feeling of tiredness which is distinct from weakness, and has a gradual onset. Unlike weakness, fatigue can be alleviated by periods of rest. Fatigue can have physical or mental causes. Physical fatigue is the transient inability of a muscle to maintain optimal physical performance, and is made more severe by intense physical exercise.