Dicky

Dicky is a British colloquialism that means not functioning properly, as in ‘a dicky heart’, or it can mean unwell as in ‘feeling a bit dicky’. Both these usages date from the late 18th century. Dicky as in a detachable shirtfront or a bib dates from the early 19th century. All these usages appear to have connections to the diminutive of Dick or Richard but the association remains obscure.