(adverb) to increase or cause to increase in size or importance
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
How to use bulk up in a sentence
Schools are more than happy to help players bulk up but nothing is done to help them slim down after the cleats get hung up.College Football Fattens Players Up and Then Abandons Them | Evin Demirel | October 4, 2014 | THE DAILY BEAST
He has watched his colleagues bulk up when the preferred silhouette was more muscular.J. Crew Model Armando Cabral: Fashion’s Exotic Boy-Next-Door | Robin Givhan | November 27, 2012 | THE DAILY BEAST
Also, he lifted weights with his teeth to bulk up his neck and trapezius muscles.
Chris Evans endured months of nausea-inducing workouts to bulk up for Captain America: The First Avenger.
In recent months, Cameron has sought to bulk up his shadow cabinet.
Wells's clerks, Bennett's "cards" and even Conrad's Russian villains do not "bulk up" against them.Instigations | Ezra Pound
Mother Corey heaved his bulk up slowly, wheezing, and indicated his chair at the head of the table.Police Your Planet | Lester del Rey
Nishikanta bellicosely shouldered his vast bulk up to the captain, opened his shirt, and exposed his revolver.Michael, Brother of Jerry | Jack London
Boil 15 minutes; filter and add enough water to bring the total bulk up to 600 cc.The Medicinal Plants of the Philippines | T. H. Pardo de Tavera
He sprang to his feet, found Grim heaving his bulk up more slowly.Slaves of Mercury | Nat Schachner