Millennial's successor, informally / TUE 5-21-24 / Purifying filter acronym / Fruit also known as calabash / Outbuilding for many a historic home / Kind of motor used in robotics / Post-panel sesh / Toffee bar brand since 1928 / Classic video game with the catchphrase "He's on fire!"

Constructor: Zachary David Levy

Relative difficulty: Medium-Challenging (**for a Tuesday**—just a bit harder than normal)

THEME: BABYPROOF (63A: Make safer, in a way ... or what the starts of 17-, 27-, 38- and 52-Across might be?) — phrases that begin with things associated with a baby:

Theme answers:

• CRIB NOTES (17A: Cheat sheets)
• BOTTLE GOURD (27A: Fruit also known as calabash)
• CARRIAGE HOUSE (38A: Outbuilding for many a historic home)
• MOBILE PHONE (52A: Counterpart to a landline)

Word of the Day: BOTTLE GOURD (27A) —

Calabash (/ˈkæləbæʃ/; Lagenaria siceraria), also known as bottle gourd, white-flowered gourd, long melon, birdhouse gourd, New Guinea bean, New Guinea butter bean, Tasmania bean, and opo squash, is a vine grown for its fruit. It can be either harvested young to be consumed as a vegetable, or harvested mature to be dried and used as a utensil, container, or a musical instrument. When it is fresh, the fruit has a light green smooth skin and white flesh.

Calabash fruits have a variety of shapes: they can be huge and rounded, small and bottle-shaped, or slim and serpentine, and they can grow to be over a metre long. Rounder varieties are typically called calabash gourds. The gourd was one of the world's first cultivated plants grown not primarily for food, but for use as containers. The bottle gourd may have been carried from Asia to Africa, Europe, and the Americas in the course of human migration, or by seeds floating across the oceans inside the gourd. It has been proven to have been globally domesticated (and existed in the New World) during the Pre-Columbian era.

There is sometimes confusion when discussing "calabash" because the name is shared with the unrelated calabash tree (Crescentia cujete), whose hard, hollow fruits are also used to make utensils, containers, and musical instruments. (wikipedia)

This was sluggish for me. Maybe it's because I know the term as CRIB SHEET, so when I got CRIB I was ... out of ideas Maybe it's because [Sneak previews] are not really the same as PROMOS. A "sneak preview" is "a special showing of something (such as a movie, play, or product) before it becomes available to the general public." And while I guess you could say that a "sneak preview" is, in fact, promotional, the term "PROMOS" usually refers to something much shorter than a full performance: a short film, video, movie trailer, etc. Maybe the trouble was that I am 54 and still can't spell LADLES ("lAdElS?"). Or that I've never heard anyone actually say NOBS for "heads" (18D: Noggins) (I'd've gone with NABS or even NIBS before NOBS there). Or that I don't know what a BOTTLE GOURD is, really, and only half-know the term CARRIAGE HOUSE. Or that MOBILE PHONE is much less used where I come from (i.e. planet Earth) than "cellphone." Or that I couldn't quite parse "OH NEAT!" for a few beats, or couldn't remember that SERVO was a thing (37D: Kind of motor used in robotics). Or maybe I'm just adjusting to this new hot weather. Whatever it was, it was something. I don't really get the revealer. Do the crib and bottle and carriage and mobile prove ... that there's a baby in the house somewhere. Nice deduction, Sherlock. Why are we looking for the baby? Shouldn't we know where the baby is? Are we detectives? kidnappers? The whole "proof" angle needed to be more tightly wed to the theme concept for it to really work. This is just a remedial "first words associated with"-type puzzle pretending it's something more.