WORDS
Words are the elements of all languages; they are born, live and die. Their form and uses change during the history of the language.

Primitive Words
These words called primitive are those original words that once introduced into Basque helped to make other words called derived.
Ex. argi, light, is primitive; argitu, lighted or lit, is derived.
Some words are onomatopoeic or imitate a sound. Ex. kuku, cuckoo; kaska, shock; uhuri, shout; firfira, rustling leaves.
Other words are conventional terms, that come from an older root and borrowed from another language such as argi, light, is a primitive word of mediterranean origin whose root is arg-.

Although most languages of the world borrow words from the Indo-European, it is mysterious how many foundational Basque words cannot be linked to source which makes it difficult to classify Eskuara in the Indo-European Language Classification.

The root is the part of the word that governs the general meaning of the word. It is usually composed of a few letters and is more or less transformed in all the words of a certain word family: in argi, light, arge, obscure, argal, scattered or sparse light, artizar, morning star, the root arg-, means light or brightness, but the root cannot be used alone. In the case of har, this is a word, which means taken, and used without suffix is used in the following: Ex. har eskuin, take a right (as in directions).

The radical is what remains of a word once you remove the ending; often mistaken with the root. Therefore, in hartu, taken, the radical is har, which is one in the same as the root. In the word argitu, lighted, the radical is argi and the root arg-.

The ending of the word clairifies the type, number, person, time, mode or function. In hartu, taken, and argitu, lighted, -tu makes the word a participle.

Derived Words
Derived words are those that come from other words. However we reserve this name for words that are formed from another word and one or many suffixes.

A suffix is the part of the word that is added to the end of the root word - adding an idea to that expressed by the root. Ex. argitzaile, lighter; argimendu, enlightenment; argitsi, bright, are all derived from argi: -tzaile, -mendu, -tsu, are suffixes.

In other cases words are derived by combining several prefixes. Ex. sagar-arno, cider (sagar, apple + arno, wine); ber-hogoi, forty (re-twenty).

A prefix is the part added to the front of the root word to change its meaning. Ex. desegin, undo, is composed of egin, to do, berphiztu, risen or rise again, is composed of phiztu, rise: des and ber are prefixes.

Special example of a word composed of a prefix, root and suffix. - irakusle, viewer, has a prefix ira-, to have, a root -kus-, see, and a suffix -le, which means "a thing" so "a thing to have you see".

Words Groups
We group words that are formed from the same root word. The root kar, for example is of celtic origin gives us a group of words that convey the idea "to take or bring."
karga, load; karro, float; karreo, charriot; kargu, function; kargatu, to load; karreatu, cart along; ekarri, to bring; ekarle, carrier; ekartzale, carrier; ekargaitz, unbearable.

egari, to bear or support; erakarri, trainer or take back; erakarpen, attraction.

All these words are from the group Ekarri, to take or bring, root kar.