What technique is used to ensure that voice messages containing unusual words are received correctly?
Why Unusual words, call signs, and proper names are easily garbled by noise, fading, or accents, so traffic handlers spell them out letter by letter using the standard ITU/NATO phonetic alphabet (Alpha, Bravo, Charlie, Delta...). Each phonetic word sounds distinct from the others, so even a partly copied syllable still identifies the letter. In formal message handling, the spelled group is normally preceded by "I spell" so the receiving operator knows what is coming.
Watch out "QSR" is not a valid Q signal for asking for a repeat (QRS means send slower, and a repeat request is normally QRM/QSM related or just "say again"), and mixing voice with Morse is not a recognized voice net practice, so the all-of-these choice fails too.
Weird word? Say it in phonetics: "I spell, Whiskey Echo Indigo Romeo Delta."