Zygote, Universe, and Yttrium
The two words "earth science" and "echo" are not the guide words for an earthquake. Earth science is the study of the Earth and its processes, while echo refers to a reflected sound wave. An earthquake is a sudden shaking of the ground caused by tectonic plates shifting beneath the Earth's surface.
Not in any dictionary I tried (two of which contain over 250,000 words each).
There are no two-letter words beginning with V. Sorry!
scientia
The words "Aardvark" and "Aardwolf" typically appear at the beginning of English dictionaries.
...are two words beginning with C?
Alliteration is the repetition of consonants at the beginning of two or more words immediately succeeding each other, or at short intervals as a form of rhyme.
observational knowledge
I can think of two dwarf and dwell.
circle and circumference. circular, circulatory,
Some words beginning with 'bi' meaning two are: biannual, bimonthly, biweekly, bicentennial, binary, biathlon, bisexual, biped, and bipartisan.
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