The article presents the words with highest index of availability on the basis of semantic fluency tests. The conceptual stability of highly available words in various semantic categories enables them to be classified as semantic prototypes according to the theory of prototype. The aim of this article is to compare the semantic prototypes in nine semantic categories from different lexical availability studies: those carried out in Spanish as a mother tongue and Spanish as a foreign language (with Slovene, Finnish, Turkish, Chinese students and students of various other mother tongues who studied Spanish in Madrid and Salamanca). The informants who come from different countries and cultures and speak different first languages demonstrate that human beings share the same or similar categorization and universality of semantic prototypes.