The Spanish word 'confiable' (meaning 'trustworthy') comes from combining the verb 'confiar' ('to trust') with the suffix '-able' (meaning 'capable of'). The verb 'confiar' itself comes from the Latin word 'confidere', which was formed by joining two Latin elements: the prefix 'con-' (meaning 'together, with') and 'fides' (meaning 'faith, trust'). So literally, something that is 'confiable' is 'capable of being trusted'.

Some simpler related Spanish words include 'confiar' (to trust), 'confianza' (trust, confidence), and 'confidente' (confidant). All these words share the same Latin root 'confidere' and revolve around the concept of trust and confidence.

English speakers might recognize the connection to words like 'confidence', 'confide', and 'confidential', which all come from the same Latin root 'confidere'. Just as 'confiable' means 'trustworthy' in Spanish, these English words all relate to trust and faith - when you have confidence in someone, you trust them; when you confide in someone, you trust them with your secrets; and confidential information is information that's trusted only to certain people.