Syntactic words don't always correspond to orthographic words, i.e. to a sequence of letters separated from other sequences of letters by a space.
Here are typical problematic cases for English:
- clitics: are phonologically dependent on their host and often orthographically connected (cannot, I'm). Syntactically they are words of their own (can not, I 'm).
- Possessive 's : The possessive 's is a word of its own. (Pat's car = 3 words!)
- compounds: often parts of compounds are separated with a space in English, i.e. they appear as distinct orthographic units. Nonetheless they are single words from the perspective of syntax. Example: telephone directory.
- multi-word expressions: Combinations such as in front of or of course are often considered "words with spaces". Nonetheless, in contrast to the compounds with internal spaces, here the combinations are not formed according to morphological rules, but are combinations of syntactic words. Thus, in front of consists of three syntactic words: in, front, of.