Question

He began to fill out once he started college.  IPAhttps://en.wiktionary.org/wiki/Wiktionary:International_Phonetic_Alphabet(keyhttps://en.wiktionary.org/wiki/Appendix:English_pronunciation): /fɪl aʊt/

Accepted Answer

(intransitivehttps://en.wiktionary.org/wiki/Appendix:Glossary#intransitive) To have one's physiquehttps://en.wiktionary.org/wiki/physique expand with maturityhttps://en.wiktionary.org/wiki/maturity or with surplushttps://en.wiktionary.org/wiki/surplus weighthttps://en.wiktionary.org/wiki/weight.

Sentence	He began to fill out once he started college.
Definition	( intransitive https://en.wiktionary.org/wiki/Appendix:Glossary#intransitive ) To have one's physique https://en.wiktionary.org/wiki/physique expand with maturity https://en.wiktionary.org/wiki/maturity or with surplus https://en.wiktionary.org/wiki/surplus weight https://en.wiktionary.org/wiki/weight .
Pronunciation	IPA https://en.wiktionary.org/wiki/Wiktionary:International_Phonetic_Alphabet ^{(key https://en.wiktionary.org/wiki/Appendix:English_pronunciation )}: /fɪl aʊt/

Began Fill Started College One's Expand Fɪl Aʊt