We have defined stems as lexical elements which cannot be used on their own (1.2.1, 1.4). The examples in 9.4 will illustrate stems in combination with prefixes and suffixes, e.g. pericarp 'seed vessel' (Greek carpos 'fruit'), amorphous (Greek morphe 'form'), ovoid 'egg-like' (Latin ovum 'egg'), and stems in combination with one another, e.g. carnivore 'flesh-eater' (Latin caro-'flesh', vorare 'to devour'), and with words, e.g. photoallergy 'allergy caused by light'. Stems belong exclusively to the Latin-and Greek-derived area, or stratum, of the vocabulary. In 9.2 we shall look at more precise uses of the term 'stratum', and in 9.3 at dependent bases like those in optimize or ventriloquist, which can be related to English words, as well as stem bases like -carp-, -morph-and -vor-, which cannot.