He kept riffing between verses to keep the crowd engaged.

Her riffing during rehearsal inspired the band to change the arrangement.

The doctor prescribed rifabutin, a bactericidal antibiotic used primarily to treat tuberculosis that works by inhibiting the bacteria's DNA-dependent RNA polymerase.

The new rifa- derivative showed potent activity against multidrug-resistant tuberculosis strains in vitro.

After discovering new nests, the county organized a rapid response team to contain RIFA before they spread to residential areas.