Or search: ai, cdc, ins, irs, usa, gao, arda, dint, disa, navy, nist, noaa, osha, tool, afrl
3 Syllables: SUU
agencies, anciently, flagrantly, halfpenny, masonry, patiently, vacancies, vacancy
4 Syllables: USUU
complacency, complacently, impatiently, mistakenly

Found 12 words across 2 groupings.