In the Nif'al form nisba`, " to swear," in the derivative subst.
From the root idea of obligation to serve or give something in return, involved in the conception of duty, have sprung various derivative uses of the word; thus it is used of the services performed by a minister of a church, by a soldier, or by any employee or servant.
Thiourea and many of its unsymmetrical derivatives have marked physiological action; thiourea causes a slowing of the pulse and respiration, cardiac failure, and death in convulsions; phenyl-, ethyland acetyl-thiourea are actively toxic. The most important derivative pharmacologically is allyl-thiourea, also known as thiosinamine or rhodallin, NH2 CS NH CH2 CH:CH2.
It is only in derivative words that this vagueness is avoided.
In this case it is readily seen that isomerism introduces itself in the three carbon atom derivative: the propyl alcohols, expressed by the formulae CH 3 CH2 CH 2 0HandCH 3 CHOH CH3, are known as propyl and isopropyl alcohol respectively.