Now, I've heard of the screaming abdabs* but abjabs are new to me.
They're writing systems which don't have any signs for vowels.
All abjads I know about come from the Middle East, and developed from Egyptian hieroglyphs. Abjads are much simpler to learn and to write than hieroglyphs, but they do have the disadvantage of making it a bit harder to be sure what people are trying to say.
I am wearing a hat would come out m wrng ht, for example.
The first abjad was created by those busy people the Phoenicians, and they, top traders that they were, sold the idea all over the place.
Now, as I have just demonstrated, vowels are jolly useful, and now just about all modern abjads are 'impure' which means that they do have the odd vowel sign when it's really necessary. Hebrew, for instance, uses hardly any vowel symbols in writing for adults (though there are symbols to help children who are learning to read), but it's no longer completely vowel-free.
T's nl snsbl, ftr ll.
Word To Use Today: abjad. Oh dear...it won't be easy to use the word abjad, will it. Perhaps this had better be a word to think today.
The word abjad was made up by Peter T Daniels. It replaced the rather lovely term consonantary.
The form of the word was inspired by the first four letters of the Arabic alphabet: ABGD.