Complex words containing native elements with spatial meanings like down, in, off, on, out, over, under are usually referred to as compounds (cf. Jespersen 1942; Marchand 1969; Meijs 1975), since such elements also function independently, in prepositional phrases and phrasal verbs. In discussing their role in word formation, we shall use the traditional term 'particle'. Particles figure both as initial elements of verbs, adjectives and nouns like downplay, inbuilt, upkeep (5.2), and as final elements in nouns like playback or pay-out (5.4), complex words transpositionally related to phrasal verbs (1.2.2). As initial elements of words, particles have much in common with the prefixes of Chapter 3, many of which are related to Latin and Greek prepositions and adverbs (and many of which, as we noted in 3.1, can occasionally be used as words). Both prefixes and particles are attached to verbal bases to form verbs (precook, overlook), to verb-related adjectival stems (interleaved, under-mentioned) and to verb-related nominal stems (subcontractor, onlooker). Both attach to nouns in attributive and predicative expressions 'intercity train', 'offshore island', 'the policy is anti-car', 'editing is on-line', and both can modify non-derived nouns (super-volcano, outfield). Certain initial particles, semantically distinct from their independent homonyms, occur productively in series of items and are thus even more like prefixes. These particles are out in verbs, and over and under in verbs, adjectives, and deverbal and deadjectival nouns (5.3).