Something that is coherent holds or sticks together firmly, with resistance to separation (that is, it coheres). Coherent, ultimately from the Latin co- ("together") and haerēre ("to stick or cling"), entered English in the 16th century and almost from the beginning was used both of physical things ("coherent stone") and of things which hold together in a much less palpable way ("coherent thoughts"). Its antonym, incoherent, entered the language some decades later. Like coherent, incoherent can be applied to both the tangible and the intangible. But, whether we are speaking of sand or logic, all things incoherent have one thing in common: they do not hold together, literally or figuratively, in a unified or intelligible whole.