He sent ______ word that he would come soon.

Concept

In English, certain nouns act as fixed, idiomatic expressions with a verb and are treated as uncountable in that sense. The phrase "to send word" means "to send a message or convey news." Here "word" does not refer to a single dictionary word but to information as an uncountable mass noun, so it takes no article (no a/an/the).

Application

The sentence is: "He sent ___ word that he would come soon." The verb "send" combined with "word" forms the set idiom meaning "to inform / let someone know." Because "word" here is uncountable and idiomatic, the slot stays empty:

"He sent word that he would come soon." = He let people know / sent a message that he would come soon.

Contrast

• "a" / "an": these are indefinite articles for singular countable nouns. "Word" in this idiom is uncountable, so a singular countable marker does not fit; "a word" would mean one single spoken/written term (e.g., "say a word"), which changes the meaning.

• "the": the definite article points to a specific, identifiable noun. The idiom "send word" refers to news in general, not one particular previously-mentioned message, so a definite marker is out of place.

• no article: matches the uncountable, idiomatic use of "word" = a message, which is exactly what the sentence intends.

Result: the blank correctly stays empty — no article needed.