Earth formed around 4.54 billion years ago by accretion from the solar nebula. Volcanic outgassing probably created the primordial atmosphere and then the ocean; but the atmosphere contained almost no oxygen and so would have been toxic to most modern life including humans.
Euthyroid is the state of having normal thyroid gland function. Examples of a nonfunctioning thyroid gland may be hypothyroidism, hyperthyroidism, or thyroiditis.
Noun. 1. steroid-any of several fat-soluble organic compounds having as a basis 17 carbon atoms in four rings; many have important physiological effects. organic compound-any compound of carbon and another element or a radical. ketosteroid-a steroid containing a ketone group.. steroid-any of several fat-soluble organic compounds having as a basis 17 carbon atoms in four rings; many have important physiological effects. organic compound-any compound of carbon and another element or a radical.