Science words are mostly made from two roots: ordinary, everyday words get a new, strict definition for use in that particular branch of science; or an entirely new word is made up for the concept in question. When the terminology for a science concept is not derived from everyday words, its is most often either based on the classical languages, Greek and Latin, or made as an acronym for a description of the concept. 'Photosynthesis' is from Greek, 'photos' from 'phos', meaning light, and 'syn-thesein', to bind together. 'Laser' is an acronym for Light Amplification by means of Stimulated Emission of Radiation. This work is often done in a systematic way (Picht and Draskau 1985; Myking 1998).

This means that, in contrast to most of the words we encounter in our daily lives, the conceptual content of a scientific term is often indicated in the term itself.

For sign languages, the root of the everyday word is more often given, or easy to spot. This is called the 'iconicity' of the sign languages. This does not mean that this root is in the mind of the signer or the listener, the signs convey meaning in just the same way as words do, by being associated with a concept in the mind. A child signing 'milk' will think of the white fluid to drink, and not of the operation of milking a cow. But when signing about things in the world that we can see, using signs that we can also see, there will easily be a closer connection between the things and the signs. This has both a positive and a negative side to it.

The positive side is that it often clarifies things, and gives the sign language a richness of nuances in expression. From the 'drive a vehicle' sign in Norwegian Sign Language (NSL) you will not only be able to see whether it is a baby tram, a bicycle or a car that is being driven; but you can also see the size of the vehicle and the manner in which it is driven, as well as direction, speed, etc.

On the other hand, there are two points on the negative side:

1) one concept will get conveyed by two or more different signs, according to circumstances. This homonymy, or polysemy, which also occur in our everyday languages, is dealt with in terminology work by the strict definition of which term/s belong to which concept, and terminologists are always trying to avoid this ambiguity (Myking 1998). If a teacher or interpreter for deaf students is not aware of this problem, it can make it difficult for the student/s to grasp the overall concept.