It obviously is a Spanish or Mexican Spanish word. I can’t find it in either Spanish-English dictionaries I have at home. Babelfish online translating service is no help and neither is Google.
What does “Mamacita” mean?
(P.S. Please forgive me if it is a swear or indelicate word 
.)
“-cita” is a diminutive suffix that might be used for affectionate purposes – so “Mamacita” means “little mama” or “Sweetie-pie Mom.”
A better translation would be Mommy.
The -ita or -ito ending is indeed a diminutive. The English equivalent would be -y or -ie.
Haj
Wow.
I always thought it might mean “mama”, which, as we all know, is a rather different word than “mommy”. You might say “come on, pretty mama”, but you wouldn’t be caught dead saying “come on, pretty mommy”.
If it is “mommy”, then that scene from “Y Tu Mama Tambien” kinda takes on a whole new quality…
To more directly pose Loopydude’s question – what are the connotations (as opposed to definition) of mamacita in actual spoken Spanish? Obviously the answers will differ depending on context, as do the connotations for English “mama”.
A lot depends on context. Mostly I’ve heard it used in a sentence such as {I}”Ay mamacita!,{/I] from guys to female passersby, in which case it means something along the lines of “hey, baby!” or “hey, cutie pie!” But that may just be a function of where I hang out. 
(And where the heck did my upside-down exclamation point go?)
I’ve only ever heard mamacita in the catcall context, just as I’ve heard “Hey, Mommie!” in the catcall context as well.
My late stepmother’s son’s first wife was Latina, and she (wife) called her MIL (my stepmother) “Mamacita.”
As far as I’ve ever encountered, it’s used mainly in a sexual context, and isn’t usually used to mean “mama” as in a child addressing it’s mother. It’s like guys at a construction site saying “Hey, hot mama!” to a woman passing by.
In general, Spanish speakers are much more likely to use words like “Mami” or Popi" (Mommy or Daddy) as terms of endearment when addressing lovers than English speakers are.