1. Not able to be counted (e.g. because too many to count) 
2. (grammar) of a word that does not have a plural form

Encyclopedia: Uncountable

• clogging
• cloggy
• cloisonné
• cloister
• cloistered
• cloistral
• Clomid
• clomiphene
• clomiphene citrate
• clomipramine
• clomp
• clon
• clonal
• clone
• clonic
• clonidine
• cloning
• clonk
• clonus
• cloot
• Clootie
• Cloots
• clop
• clopidogrel bisulfate
• clopping