ground·mass 
(groundmăs′)
(groundmăs′)n.
The fine-grained crystalline base of porphyritic rock in which larger crystals are embedded.
- hypochondrium
- hypocorism
- hypocoristic
- hypocoristically
- hypocotyl
- hypocretin
- hypocrisy
- hypocrite
- hypocritical
- hypocritically
- hypocycloid
- hypoderm
- hypoderm
- hypodermal
- hypodermic
- hypodermically
- hypodermic injection
- hypodermic needle
- hypodermic syringe
- hypodermis
- hypodynamic
- hypoesthesia
- hypoeutectic
- hypogastric
- hypogastrium