first law
noun
: the most important principle
He teaches his students that balance is the first law of architecture.
Examples of first law in a Sentence
Recent Examples on the Web
Arguing about snow in subfreezing temperatures can remind you of the first law of thermodynamics—that snow can’t be created or destroyed.
—
Naaman Zhou, New Yorker, 3 Feb. 2026
This first law offered monthly benefits only for disabled people over age 50.
—Tom Margenau, Dallas Morning News, 18 Jan. 2026
For example, tidal stresses occur because Europa's orbit around Jupiter is not perfectly circular but rather eccentric, in accordance with Johannes Kepler's first law of orbital motion.
—Keith Cooper, Space.com, 9 Jan. 2026
The Clean Air Act of 1970 was the first law to require the EPA to set uniform nationwide standards for air quality to protect the air people breathe.
—James Salzman, The Conversation, 5 Jan. 2026
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Naaman Zhou, New Yorker, 3 Feb. 2026
This first law offered monthly benefits only for disabled people over age 50.
—Tom Margenau, Dallas Morning News, 18 Jan. 2026
For example, tidal stresses occur because Europa's orbit around Jupiter is not perfectly circular but rather eccentric, in accordance with Johannes Kepler's first law of orbital motion.
—Keith Cooper, Space.com, 9 Jan. 2026
The Clean Air Act of 1970 was the first law to require the EPA to set uniform nationwide standards for air quality to protect the air people breathe.
—James Salzman, The Conversation, 5 Jan. 2026
See All Example Sentences for first law
Cite this Entry
“First law.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/first%20law. Accessed 14 Feb. 2026.
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