Small one: valvule.
[French, from Latin -ulus, -ula, -ulum, diminutive suff.]
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.
suffix forming nouns
indicating smallness: globule.
[from Latin -ulus, diminutive suffix]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
a suffix occurring in loanwords from Latin, orig. diminutive nouns (capsule; globule; nodule) or noun derivatives of verbs (ligule).
[< French < Latin -ulus, -ula, -ulum diminutive formative with nouns of the 1st and 2d declensions «*-el- (compare -cle1, -elle, -ole1)]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.