Gain access to thousands of additional definitions and advanced search features—ad free! JOIN NOW
: a dicarboxylic acid C10H14N2O4 that is derived from pyrrole, that is found in the urine in acute porphyria, and that on condensation of four molecules yields uroporphyrin and other porphyrins
Resources for porphobilinogen
porphyria cutanea tarda
Comments on porphobilinogen
What made you want to look up porphobilinogen? Please tell us where you read or heard it (including the quote, if possible).
a trusted follower
Get Word of the Day daily email!
Difficult Vocab Quiz
Test your visual vocabulary with our 10-question challenge!
Test Your Knowledge - and learn some interesting things along the way.
Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!
Semantic bleaching and the power to amaze
Cans of worms, wild-goose chases, and more
Words from the week of 11/16/2018
This is just to say / Don't confuse them
And is one way more correct than the others?
The story of an imaginary word that managed to sneak past our editors and enter the dictionary.
How to use a word that (literally) drives some people nuts.
The awkward case of 'his or her'
Another round of challenging vocab!
(Secret October WOTD Quiz)
SCRABBLE® fans, sharpen your skills!