Today's Word

Hermetic

her-MET-ik

Definition

(adjective) Completely airtight and sealed; or, completely closed off from outside influence or interference.

Example

The research team worked in hermetic isolation for three months, communicating with no one outside the facility.

Word Origin

From the name Hermes Trismegistus — “Hermes the Thrice-Great” — a legendary Greco-Egyptian figure credited with inventing a miraculous airtight seal used in alchemy. “Hermetic sealing” was named after him, referring to a glass-fusion technique that made containers completely airtight. The word entered English in the 17th century, first in alchemical contexts before broadening into its modern senses.

Fun Fact

The “Hermetic tradition” is a body of philosophical and spiritual writing attributed to Hermes Trismegistus, blending Greek philosophy, Egyptian religion, and early mysticism. It was wildly influential during the Renaissance — figures like Marsilio Ficino and Giordano Bruno believed it represented a secret ancient wisdom older than Christianity. Modern Freemasonry, Rosicrucianism, and many esoteric traditions trace spiritual lineage to Hermetic philosophy. The word “hermetically sealed” still carries a faint echo of that sense of sacred, impenetrable mystery.

Previous Words

Efficacious

Today's Word

Efficacious

ef-ih-KAY-shus

Definition

(adjective) Capable of producing the desired result; successful in achieving the intended outcome.

Example

The new treatment proved remarkably efficacious in clinical trials, reducing symptoms in over ninety percent of patients within the first two weeks.

Word Origin

Efficacious derives from the Latin efficax, meaning “powerful” or “effectual,” rooted in efficere — “to bring about” or “to accomplish” — built from ex- (“out”) and facere (“to make” or “to do”). The same root gives us effect, efficient, and efficacy — a family of words all built around the idea of something being done and producing a result. It entered English in the 16th century, used predominantly in medical and philosophical contexts to describe remedies or arguments that actually worked.

Fun Fact

The history of medicine is largely a history of distinguishing the efficacious from the merely plausible. For centuries, bloodletting was considered one of the most efficacious treatments available — practiced by physicians from ancient Greece through the 19th century for conditions ranging from fever to mental illness. George Washington died in 1799 partly as a result of aggressive bloodletting performed by his own doctors in response to a throat infection. It wasn’t until the rise of controlled clinical trials in the 20th century that medicine developed reliable tools for separating treatments that actually worked from treatments that merely seemed to — a distinction efficacious had been waiting two thousand years for medicine to catch up with.

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Hermetic

Definition

Example

Word Origin

Previous Words

Efficacious

Efficacious

Definition

Example

Word Origin

Efficacious

Penurious

Unctuous

Adumbrate

Lurid