Final answer:
Synthetic languages are defined as languages with internal grammar of the word, using inflections or alterations to word forms to express grammatical relationships. An example is German, where 'gesprochen' encapsulates the verb and tense within a single word.
Step-by-step explanation:
Synthetic languages are characterized by their use of internal grammar within words. This means they often use inflections or alterations to a word's form to express grammatical relationships or functions, rather than relying solely on word order or prepositions.
In the context of the provided options, synthetic languages are best described as: 1) Languages with internal grammar of the word. This refers to the morphology of the language, where a single word can contain a lot of syntactic information, such as tense, case, mood, and gender, among other grammatical distinctions.
For example, in German (a synthetic language), the word 'gesprochen' ('spoken') includes both the verb 'sprechen' ('to speak') and the past participle marker 'ge-', indicating past tense. Unlike analytic languages, which would use separate words to convey the same meanings, synthetic languages encode this information within the words themselves.