“Como” in Spanish has diverse semantic values. “Quomodo” in latin originally was used as an interrogative, an exclamative and a relative adverb and but throughout its evolution towards "como" in Spanish, its use is expanded as an adverb in approximate, comparative and coordinate constructions and became to be used as a conjunction in causative and conditional sentences. In modern colloquial Spanish, "como" has topicalizer role at pragmatic level. In order to explain the semantic divergence of "como", in the present study I applied grammaticalization theory with the prototype categorization. In the first step, among the original values of “quomodo”, the use as a relative adverb in adverbial clauses generated its basic meaning: "cognitive proximity" between two entities or attributes (como A = A') and became to assume the cognitive schema A'≒A. In the second step, the uses of "como" as a preposition or an adverb in approximate, comparative and coordinate constructions were derived from this basic cognitive meaning. In the third step, once firmly established its use of multivalue as an adjunct, "como" became to be used as a conjunction whose function is adjunct as well but at sentence level. Finally, its grammacalization process culminated in its use as a topicalizer at pragmatic level. This phenomenon can be explained as subjectification, the last step of grammaticalization.