Half hour

[U]pon the whole she spent her time comfortably enough; there were half hours of pleasant conversation with Charlotte, and the weather was so fine for the time of year, that she had often great enjoyment out of doors.

Every half hour or so one or the other would steal off with snowshoes and toboggan to make the round of the holes, often returning with half a dozen fish that together weighed perhaps twelve pounds, perhaps twenty-four pounds; […]

I was a night owl and could be a bit grumpy (mean, Michelle would say) within the first half hour or so of getting out of bed.

Your stomach secretes ghrelin in pulses every half hour, sending subtle chemical impulses to your brain—almost like subliminal biological messages (carrot cake, carrot cake, carrot cake).