This answer to a question about the Shuttle reentry begins:
Skipping reentries aren't unheard of. The Apollo command module performed a single skip when returning from lunar missions.
but Wikipedia's Boost-glide; Reentry vehicle use is less assertive about the "skippiness" of Apollo's reentry:
Reentry vehicle use
The technique was used by the Soviet Zond series of circumlunar spacecraft, which used one skip before landing. In this case a true skip was required in order to allow the spacecraft to reach the higher-latitude landing areas. Zond 6, Zond 7 and Zond 8 made successful skip entries, although Zond 5 did not. The Chang'e 5-T1, which flew mission profiles similar to Zond, also used this technique.
The Apollo Command Module used a skip-like concept to lower the heating loads on the vehicle by extending the re-entry time, but the spacecraft did not leave the atmosphere again and there has been considerable debate whether this makes it a true skip profile. NASA referred to it simply as "lifting entry". A true multi-skip profile was considered as part of the Apollo Skip Guidance concept, but this was not used on any crewed flights. The concept continues to appear on more modern vehicles like the Orion spacecraft, using onboard computers.
The FAA's Returning from Space; Reentry 4.1.7 says on page 4.1.7-311:
On the other hand, if the vehicle enters above the upper boundary (overshoots), it won’t experience enough drag and may literally skip off the atmosphere, back into space. If designers aren’t careful, these competing requirements may lead to a reentry corridor that’s too narrow for the vehicle to steer through!
Which to me seems to invoke "skip" without the necessity of any drag; an elliptical or hyperbolic trajectory can simply loose some velocity while passing through an atmosphere, perhaps as an aerobraking maneuver with or without using lift, but I don't see how that would be called skipping. "Skip" doesn't appear in that Wikipedia article.
From history.nasa.gov Apollo 11 Day 9: Re-entry and Splashdown:
191:48:46 Armstrong: Okay, Ron. For MIDPAC: 000, 152, 001; 194:46:06, 267; plus 13.32, minus 169.17; 06.4; 36194, 6.49; 1404.5, 36275; 195:03:06, 0028, 1.54, 0.84, 2240, 180, 4.00, 02:13; 00:17, 03:51, 09:02; 45, 018.9, 27.7; none available; lift vector, Up; GDC align, Vega and Deneb, roll 078, pitch 223, yaw 340. Use non-exit EMS. EI minus 30 horizon check, 194:33:06, pitch 298. Initial bank angle in P67 may not be full lift, and we will get P65 but no P66.
(comments) If the IMU fails and they need to have a backup alignment on the Gyro Display Couplers, then they should use stars Vega and Deneb. Aligning to them would represent the following attitude; roll, 078; pitch, 223; yaw, 340. Although they are extending the length of the entry by invoking the skip-out software, they will not be exiting the atmosphere so therefore they should use the part of the EMS scroll that pertains to a non-exit entry. When making a check of the horizon angle 30 minutes prior to Entry Interface, their pitch angle should be 298°. In a conventional entry, P64 is followed by P67. For a skip-out re-entry, P65 and 66 are employed to handle the exit and entry parts of the skip. In this case, because they are extending the re-entry but not actually skipping out, P66 will not be invoked and instead, P65 will lead directly to P67. The crew are also informed that they may not be in a full-lift (heads-down) attitude when they enter P67.]
I don't understand that explanation, but I think that I understand that the capsule's reentry attitude produced both drag to loose energy and lift, and I'm guessing that the lift was employed to (at least) lower the rate of descent into the denser atmosphere until more velocity could be shed in order to reduce peak heating.
I also understand from the Wikipedia article that not all would like to describe this as an actual atmospheric skip, but I don't know if it's because the capsule never left and then reentered the atmosphere, or because it never even had a lift-driven ascent phase.
Question: What exactly was the planned trajectory for the Apollo capsule during reentry? Did the rate of descent flatten to zero? Did it change sign and rise at some point?
"bonus points:" Does "skip" even have a clear definition? Must it be due to lifting force or can any atmospheric trajectory that has a period of rising that follows a period of falling be called a "skipping" trajectory?