- hygrocybe acutoconica
- hygrograph
- hymenopteran
- hymenopteron
- hymenopterous insect
- hymenoxys acaulis
- hymnary
- hymenoxys grandiflora
- hymie
- hymnody
- hyna
- hynerpeton
- hyoscine
- hypanthium
- hypaethral
- hyoid bone
- hypentelium
- hynerpeton bassetti
- hyoid
- hypentelium nigricans
- hyper_eutectoid steel
- hyperactivity
- hyperactive
- hyperacusia
- hyperacusis
- hyperaldosteronism
- hyperaemia
- hyperalimentation
- hyperadrenocorticism
- hyperbola
- hyperbolic geometry
- hygrology
- hyperbilirubinemia of the newborn
- hygrophoraceae
- hygrophorus caeruleus
- hygrophorus
- hygrophorus kauffmanii
- hygrophorus borealis
- hygrophorus inocybiformis
- hygrophorus marzuolus
- hygrophorus sordidus
- hygrophorus purpurascens
- hygrophorus russula
- hygrophorus tennesseensis
- hygrotrama foetens
- hygroton
- hygrophorus turundus
- hygrotrama
- hylidae
- hylactophryne