The Spanish word 'migaja' meaning 'small crumb' comes from the Spanish word 'miga' (meaning 'crumb') combined with the diminutive suffix '-aja'. The word 'miga' itself derives from the Latin word 'mica', which meant 'crumb' or 'small particle'. The addition of the diminutive suffix '-aja' emphasizes the smallness of the crumb, literally meaning 'tiny crumb'.

A simpler and more common related Spanish word is 'miga', which means 'crumb' or can also refer to the soft inner part of bread. While 'miga' refers to any crumb, 'migaja' specifically emphasizes its small size. You might hear 'miga' in phrases like 'miga de pan' (bread crumb) or 'migas' (a Spanish dish made with bread crumbs).

The English word 'mica', referring to the shiny mineral that can be split into very thin sheets, comes from the same Latin root 'mica'. The connection in meaning comes from the fact that both bread crumbs and the mineral can be found in small, flaky particles. Another related English word is 'micaceous', meaning 'containing mica' or 'having a glittery appearance like mica'.