When one who is called a prophet utters falsehood, would you not call him/her a false prophet?

When Elijah confronted the prophets of Baal, they were simply described as, "...the 450 prophets of Baal and 400 prophets of Asherah..." 1 Ki 18:19.

"Then Elijah said to the prophets of Baal..." vs 25.

"Seize the prophets of Baal.." vs 40.

Elijah described and contrasted himself as/to, "a prophet of the LORD, but Baal's prophets are 450 men." vs 22.

Your point about the word "prophet" being neutral is well taken. Whether that prophet is a true or false prophet is therefore recognized by what they do or the context. I could be wrong, but when the Bible qualifies it as "a prophet of the LORD," there is no question that that prophet is a true one. And when a prophet is described as "a prophet of Baal or Asherah," that such a one is a false prophet.

Here's another example found in 1 Ki 22. Ahab invites Jehoshaphat to go to war with him.

"And Jehoshaphat said to the king of Israel, 'Inquire first for the word of the LORD.' Then the king of Israel gathered prophets together, about 400 men...." vs. 5,6.

Jehoshaphat no doubt recognized these prophets for what they really were. So he asks:

"Is there not here another prophet of the LORD of whom we may inquire?" vs. 8

Again, the word prophet is used neutrally, but the context leaves no doubt what kinds of prophets the Bible is talking about.

Gerry