| In linguistics, a morph is a single indivisible piece carrying meaning or grammatical content. For example, in The children are playing, the six morphs are The, child-, -ren, are, play, -ing. Two of them (child, play) have a definite semantic content, and the other four are syntactic.
The affix -ing is a simple morph: the grammatical sense of continuous action is always carried by this morph.
The plural of nouns is however carried by different morphs: usually -s or -es, but in a few words -en or -ren, or zero (sheep), or vowel change (men, child-). These are all allomorphs of the one morpheme, "noun plural".
The morpheme is a high-level or "emic" concept, like an equivalence class in mathematics or a chemical element. The morph is a low-level or "etic" concept, like an allotrope of an element. Similarly in phonetics, there are phonemes, which are classes of phones grouped into allophones.
Words might not be neatly divisible into morphs. For example, men contains both the semantic part man and the morphological process of vowel change to mark plural. Two morphemes are represented by one morph. We call them two morphemes for regularity, because most other plurals do have two overt morphs.
The study of morphs and morphemes is morphology. | 
