Pluteus sesquipedalis est.

Because Latin word order is much more flexible than English word order. A very common neutral pattern is subject + complement + verb, so Pluteus sesquipedalis est is perfectly normal.

Putting est last is especially common in simple statements. You could also say Pluteus est sesquipedalis without changing the basic meaning.

Pluteus is nominative singular masculine.

Why?

• It is the subject of the sentence.
• -us is a very common nominative singular ending for second-declension masculine nouns.

So here pluteus is the thing being described.

It is an adjective.

In this sentence, it is a predicate adjective, which means it comes with the linking verb est and describes the subject:

• pluteus = the subject
• est = is
• sesquipedalis = the quality or measurement being stated about the subject

So the structure is basically X is Y.

Because not all Latin adjectives use the same endings.

Pluteus is a second-declension noun, but sesquipedalis is a third-declension adjective. Third-declension adjectives often have -is in the masculine/feminine nominative singular.

So even though pluteus is masculine, the correct adjective form is still sesquipedalis, not sesquipedalus.

They agree in gender, number, and case:

• pluteus = masculine, singular, nominative
• sesquipedalis = masculine, singular, nominative

The endings do not have to look the same. Agreement in Latin is about grammatical features, not about matching surface endings exactly.

Because Classical Latin has no articles.

So pluteus can mean:

• the pluteus
• a pluteus
• simply pluteus

English requires an article in most cases, but Latin usually leaves that to context.

It literally refers to something measuring a foot and a half.

It is built from:

• sesqui- = one and a half
• an element related to pes, pedis = foot

So the adjective means one-and-a-half-foot in measurement or a foot and a half long/high/etc., depending on context.

Not always.

By itself, sesquipedalis means measuring a foot and a half, but it does not necessarily specify whether that is:

• height
• length
• width

Usually the noun or the context makes that clear. English often forces us to be more explicit than Latin does.

Yes. Latin allows more freedom in word order because the endings show the grammar.

For example, these are all possible:

• Pluteus sesquipedalis est
• Pluteus est sesquipedalis
• Sesquipedalis pluteus est

The core meaning stays the same, but the emphasis changes a little. Putting sesquipedalis first gives extra prominence to the measurement.

In a simple Classical-style pronunciation, you could say:

PLU-te-us ses-kwi-pe-DA-lis est

A few helpful points:

• pluteus has three syllables: plu-te-us
• qu is pronounced like kw
• the stress in sesquipedalis falls on da: ses-kwi-pe-DA-lis