The name “Dejal” is pronouced “DEE-JILL”. It is not a French word, so should not be pronounced as “DAY-ZHAL” or other variations.
The name originated from the former initials of the founder of the company, David Sinclair — me. I used to be David J. Lambert, but my wife and I both changed our surnames to “Sinclair” when we got married, being people who like to make our own conventions (and we chose that name in part after my first computer, the Sinclair ZX81). Anyway, back around 1983 I needed a password, so an obvious (if simplistic) choice was something based on my initials. D.J.L. with some vowels to make it pronounceable gave “DeJaL”, and thus “Dejal” was created.
Interestingly, it turns out that “dejal” is a word in some other languages. “Dejal” is a Slovene verb, the past participle of the verb “reci”, meaning “to say, tell.” An example: “He told her that she was beautiful” = “On ji je dejal, da je lepa.” (“je dejal” = “told”). Kinda appropriate for a software publisher! It appears that “Dejal” is also a Yugoslavian or Czech name equivalent to “David”, which is also rather fitting. If you have any other examples, or corrections, please let me know.