Language is a complex and dynamic system. If we consider word meaning, which is the scope of lexical semantics, we observe that some words have several meanings, thus displaying lexical polysemy. For example, head in English means the body part and a group leader. This situation may change over time, giving rise to semantic change, whereby a word acquires new meanings or loses existing ones. For example, tweet refers to the chirp of small birds, but in recent years it has been used also to refer to a post on Twitter (cf. e.g. entry ‘tweet, v.’ in the Oxford English Dictionary). Sometimes two meanings coexist before one takes over, as in the case of the French word témoin ‘person giving testimony’, which originated from the Old French tesmoin ‘testimony/person giving testimony’, and derived from the Classical Latin word testimonium ‘testimony’ (Koch 2016: 25).