Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
reenforcement is a noun meaning "information that makes more forcible or convincing". It carries 2 recorded senses.
information that makes more forcible or convincing
“his gestures provided eloquent reinforcement for his complaints”
a military operation (often involving new supplies of men and materiel) to strengthen a military force or aid in the performance of its mission
“they called for artillery support”
military
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for reenforcement come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.