'Smile' is a Viking gift — borrowed from Scandinavian. Old English had no word for the expression.
A pleased, kind, or amused facial expression formed by turning up the corners of the mouth.
From Middle English 'smilen,' probably from a Scandinavian source akin to Swedish 'smila' (to smile) and Danish 'smile,' from Proto-Germanic *smīlijaną (to smile). Possibly related to Latin 'mīrārī' (to wonder at, to admire) through PIE *smey- (to laugh, to smile), though this connection is debated. Remarkably, Old English had no native word for 'smile' — the concept was expressed through phrases or other words until the Scandinavian-influenced
Old English had no word for 'smile.' The Anglo-Saxons used words for laughing, grinning, or being glad, but the subtle, quiet turning-up of the mouth had no dedicated term until Scandinavian settlers brought 'smilen' into English in the thirteenth century. The concept of the smile as distinct from the laugh is a medieval Scandinavian gift to English.