Lynguistykon: Language
Language is how living beings communicate, combining words and usually intonations to record or transfer meaning. How those words and intonations present themselves varies very widely among species, cultures, and even individuals. Language can be audibly, visually, or otherwise sensorily communicated. Language can be the means by which a living being communicates internally, as well.
Words
Words are ideas presented in a recognizable communication that can thereby be transferred. Communication usually but not always involves many words put together to communicate a complete idea or multiple ideas together. Letters (considered either the simplest words and/or the building blocks to words) serve a similar role within communication and the boundary between letter and word is not always clear. In some languages even basic letters already do serve essentially as words, with recorded meanings that stand on their own that can then be combined with other letters to present either deeper or altered meanings. In others, letters can generally only convey sufficient meaning ("make sense") combined together with other letters to form words.
Intonation
Intonation is attached to letters/words to either deeper or alter their meaning.