As a heraldic device, the helmet denotes wisdom and security in defence, and will have this significance in dreams. It symbolizes both protection by, and of, the Spiritual Self. In olden times, the helmet was the attribute of the warrior or hero. Whilst it covered the face, it often had the eye pieces highlighted in order to scare the enemy. Even today - as with the motorcycle helmet - it is still in dreams largely a representation of the masculine. In dreams, it will depend on whether the helmet is being worn by someone else or by the dreamer. If the former, it may have the same symbolism as the mask in that it prevents the wearer being seen. If the latter, then it is a symbol of protection and preservation. In a mans dream the helmet will represent his own virility. In a womans dream it will symbolize her attitude to the masculine. The type of helmet will be relevant, since there are now cycle and sports helmets - among others - which do not cover the face, but do protect the head, the seat of the intellect. You might also like to consult the entries for Head in Body, Hat in Clothes, Goggles, Hide/Hidden and Mask.