The Spanish verb 'complicar' (to complicate) comes from the Latin verb 'complicare', meaning 'to fold together'. This Latin word was formed by combining two elements: the prefix 'cum-' meaning 'with, together' and the verb 'plicare' meaning 'to fold'. The literal sense of 'folding things together' evolved metaphorically to mean making something complex or difficult, as multiple folds create intricate patterns and complexity.

Several common Spanish words share the same Latin root 'plicare': 'plegar' (to fold), 'explicar' (to explain, literally 'to unfold'), 'duplicar' (to duplicate), and 'aplicar' (to apply). The idea of 'folding' is present in different ways in each word - 'explicar' suggests unfolding something to make it clear, while 'duplicar' implies folding something over once to make a copy.

Many English words are related to 'complicar' through the same Latin roots: 'complicate', 'complex', 'ply', 'apply', 'implicate', 'explicate', and 'duplicate'. The element 'ply' in English preserves the original meaning of folding or layer, as seen in 'plywood' or '2-ply tissue'. The prefix 'com-' (meaning 'with, together') appears in both languages in words like 'combine'/'combinar' and 'compose'/'componer'.