A small, pointed implement for piercing materials e.g. cloth, leather etc.; a pin used to fasten hair; most familiarly, and later, a *dagger or a stiletto. Bodkin and pin (the seamstress's and hairpin) were used synonymously until the 16c and later; up to six inches or more in length, they were potentially lethal.
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.