Content Word
A word that carries a picture: nouns, main verbs, adjectives. Easy to learn, easy to point at.
Content words are the words that mean something on their own: dog, run, cold, kitchen. They form an open class, new ones are coined constantly, and they carry the actual information in a sentence, while function words hold the structure.
For learners they are the pleasant part of vocabulary: a content word can be drawn, mimed, or photographed, and flashcards suit them perfectly. Bands 3 and up of a frequency list are mostly content words, which is why progress feels faster there than in the strange function-word-heavy first band.