'weary-eyed' originates from Modern English, specifically a compound of the words 'weary' and 'eye', where 'weary' comes from Old English 'wērig' (meaning 'tired, exhausted') and 'eye' comes from Old English 'ēage' (meaning 'eye').

'weary' changed from Old English 'wērig' and 'eye' from Old English 'ēage'; the two were combined in Middle to Modern English into the compound 'weary-eyed' to describe someone whose eyes show weariness, eventually settling into the modern hyphenated form 'weary-eyed'.

Initially, 'wērig' meant 'tired' and 'ēage' meant 'eye', and when combined the phrase initially described literally 'eyes that are tired'; over time the compound retained this basic sense and also acquired a broader figurative use describing general mental or emotional weariness.