Hyma

hyma (αἷμα), means life essense, which can mean either blood, or semen. That which sustains life, or causes life.

in Greek usage hyma (αἷμα) is not merely “blood” as a mechanical fluid, but a vital substrate—the bearer of life-force, heat, lineage, and generative capacity. The nuance you’re looking for is well attested in classical medical, philosophical, and ritual Greek.

LSJ, s.v. αἷμα

hyma (αἷμα), atos (ατος), to (τό)
blood, esp. as the seat of life,
opposed to phlegma (φλέγμα), chole (χολή), etc.;also kindred, lineage, blood-relation.

LSJ explicitly frames hyma (αἷμα) as more than a substance, a vital principle.

Hippocratic medicine — hyma (αἷμα) as zoutikon (ζωτικόν)

In the Hippocratic Corpus, hyma (αἷμα) is one of the four humors, but it is consistently:

warm
moist
life-supporting

Example (summarized from De Natura Hominis):

hyma (αἷμα) predominates in youth and fertility; when balanced, it produces vigor and generation; when lost, zoe (ζωή - animated life force) departs.

Blood loss = loss of life because hyma (αἷμα) carries vitality, not merely oxygen (a modern abstraction).

Aristotle — hyma (αἷμα) and sperma (σπέρμα) are materially linked

This is the strongest support for hyma == semen (a refinement of blood).

Aristotle, Generation of Animals (Γενέσεως Ζῴων)

Aristotle explicitly teaches that:

sperma (σπέρμα) - semen is a refinement of blood
Blood is the material cause of generation
Semen is blood worked upon by heat

Paraphrase of Aristotle (GA I.18, II.3):

σπέρμα ἐστὶν αἵματος περίττωμα

Semen is a surplus / refinement of blood

Thus:

hyma (αἷμα) → sperma (σπέρμα) → animated life force (ζωή)
Semen is blood transformed, not a separate category

So when Greek authors speak of αἷμα as life-bearing, they are not excluding semen—they are placing semen within the blood-life continuum.

Galenic medicine — hyma (αἷμα) as zoutikon (ζωτικὸν) pneuma (πνεῦμα) carrier

Galen refines this further:

Blood carries πνεῦμα (vital spirit)
Different refinements of blood correspond to:
- nourishment
- vitality
- generation

Blood is not inert; it is animated matter.

Galen (De Usu Partium):

The blood is the vehicle of vitality and generation, prepared in stages toward nourishment or seed.

Again: blood = life-essence, with semen as a specialized expression.

Tragic & ritual Greek — αἷμα as life itself

In tragedy and cultic language:

hyma (αἷμα) = life forfeited
spilling blood = releasing life
hyma (αἷμα) cries out, pollutes, binds oaths

Examples:

Aeschylus, Sophocles: hyma (αἷμα) is what binds kin, curses houses, awakens Erinyes
Sacrifice: blood is offered because it contains Zoe (ζωή - animated life force), not because it is red fluid

This is why:

blood libations matter
kinship is hyma (αἷμα)
murder is hymatochusia (αἱματοχυσία) — life-pouring

Conclusion

In Greek thought:

hyma (αἷμα) = zouophoron (ζωοφόρον) hupostrouma (ὑπόστρωμα) life-bearing substrate
It can appear as:
- circulating blood
- generative semen or ejaculate (sperma (σπέρμα))
- lineage / kinship
- sacrificial vitality

hyma (αἷμα) is the vital substance that sustains and transmits life; it appears as blood in circulation and as semen in generation, differentiated by heat and function, not by essence.

Blood and semen are not different kinds of stuff
They are the same underlying substance

They belong to the same ontological category.

That is a fully classical definition (not modern).