Simple words - a basic concept of linguistics, and for most of people this term is clear intuitively. But to feel one business, and another is to give definition or to describe an algorithm of search of simple words.
1. Exclude the words consisting of several parts. They are called difficult, them, as a rule, it is possible to allocate at first sight. They have more than one root: dark blue, treasure-hunter. Having laid aside compound words, continue the analysis and selection of options.
2. Be at loss for words which describes the familiar things surrounding the person in daily occurrence. Usually for the name of basic household items use just so-called simple words. For example, the chair, a table, a case - the meaning of these names is clear to any person familiar with language. Make the list of concepts which in your opinion lay claim to "simple".
3. Carry out morphological analysis of words from your list. Find a root, the termination. If in a word there are prefixes and suffixes, then it is not simple. From morphemes there have to be only a root and the termination, for example, the sky, white, water, the earth. Indeclinable words can consist only of a root: subway, radio, kangaroo. The majority of the nouns unchangeable on cases are foreign-language loans.
4. Exclude loan words to find simple elements of the native language. Study an internal form of words. If morphemes make own sense, then the word has roots in this language. If it is absent, then before you loan. So, it is impossible to call this word simple in pure form as for source language it can be difficult or derivative.