'splay' (base of 'splayed') originates from Middle English 'splayen' or 'spleien', likely influenced by Old French forms such as 'espalier' meaning 'to spread out' or 'to lay open'.

'splay' changed from Middle English 'splayen' (used to mean 'to thrust apart, flatten') and was influenced by Old French terms, eventually becoming modern English 'splay' with senses of spreading outward and flaring.

Initially, it meant roughly 'to split, spread, or flatten out'; over time the usage narrowed and specialized to mean 'to spread outward or apart' and came to be used adjectivally (e.g., 'splayed') as well.