The Spanish word 'fantasma' meaning 'ghost' or 'phantom' traces back to Ancient Greek through Latin. It began with the Greek verb 'phaíno' (φαίνω) meaning 'to shine' or 'to appear.' From this verb, the Greeks derived 'phántasma' (φάντασμα) meaning 'apparition' or 'appearance.' This word was borrowed into Latin as 'phantasma' with the meaning 'apparition' or 'ghost,' and finally evolved into the Spanish 'fantasma' with essentially the same meaning. The semantic development from 'to shine/appear' to 'ghost/phantom' makes intuitive sense, as ghosts are traditionally thought of as apparitions that appear to people.

Some related Spanish words include 'fantasía' (fantasy), which shares the same Greek root and relates to things that appear in the imagination, and 'fantástico' (fantastic), which originally referred to something that exists only in imagination or fantasy. These words all connect to the idea of appearances or things that seem to manifest, whether real or imaginary.

English speakers can easily remember 'fantasma' by connecting it to several similar English words from the same Greek root: 'phantom' (which means exactly the same thing), 'fantasy,' 'fantastic,' and even 'phantasmagoria' (a sequence of dream-like images). The connection between these words lies in their shared origin relating to appearances and things that manifest, whether real or imaginary. The initial 'ph-' in English versus 'f-' in Spanish represents a common pattern in how Greek-derived words were adapted differently into different languages.