ghost

This word is derived from Old English gast, which in Middle English became gost.  The ghost spelling is thought to have been adopted in the fifteenth century from the Middle Dutch spelling gheest by the earliest printers and compositors who were originally from the Low Countries.  Its first appearance is in texts printed by William Caxton, but it only became common in the middle of the sixteenth century.  It is one of small number of <gh> spellings that appeared in the sixteenth century, like ghest ‘guest’ ghoos ‘goose’, gherle ‘girl’, most of which no longer survive.  The <gh> spelling was subsequently adopted in the spelling of related words, such as ghastly.  This word is etymologically related to ghost; its earliest spellings are therefore without an <h>.  The earliest example of the spelling ghastly is found in Edmund Spenser’s Faerie Queene; it was probably Spenser’s use of this spelling that ensured its wider adoption.  It may be that the preservation of the <gh> in ghastly, ghost and aghast, is due to their shared sense of ‘fear’ or ‘shock’.  While this is a tempting theory, we should also note the existence of a number of counterexamples, such as gherkin, that have the <gh> spelling but don’t share the same semantic component (unless it’s possible to be afraid of a gherkin).  Gherkin is also a Dutch borrowing, although the Dutch form gerken doesn’t have the <gh>; the earliest English appearance of the word, Samuel Pepys’s record of his first encounter with this exotic delicacy, is spelled girkin.