the·oph·yl·line (th?-?f??-l?n)n. A colorless crystalline alkaloid, C7H8N4O2, derived from tea leaves or made synthetically, used as a bronchodilator primarily to treat asthma and chronic obstructive pulmonary disease.[New Latin thea, the tea plant (ultimately from Dutch thee); see tea + phyll(o)- + -ine.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.theophylline (?????f?li?n; -?n; ????f?l?n) n (Pharmacology) a white crystalline slightly water-soluble alkaloid that is an isomer of theobromine: it occurs in plants, such as tea, and is used to treat asthma. Formula: C7H8N4O2. See also xanthine2[C19: from theo(bromine) + phyllo- + -ine2]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014the?o?phyl?line (??i ??f?l in, -?n) n. a crystalline alkaloid, C7H8N4O2, an isomer of theobromine extracted from tea leaves or produced synthetically, used in medicine chiefly to relieve bronchial spasms. [1890?95; theo-, comb. form representing New Latin thea tea + -phyll + -ine2] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.