If a creature loses all abilities, does it also lose keyword abilities like flying and trample?

When a spell or effect causes a creature to "lose all abilities," this removes every ability the creature has, without exception. Keyword abilities such as flying, trample, first strike, lifelink, and deathtouch are all classified as abilities under the rules, so they are included in this loss.

According to CR 113.1, abilities are defined broadly and include keyword abilities (CR 702.1). There is no special category that shields keyword abilities from effects that remove all abilities. The creature is left as a blank, ability-less permanent with only its base characteristics (power, toughness, name, type) remaining — and even those can be overwritten depending on the effect.

It is important to note that some characteristics can look like abilities but are not. For example, a creature's power and toughness are not abilities, so they are unaffected by losing all abilities unless the effect says otherwise. Similarly, a subtype (like "Human" or "Dragon") is not an ability and is retained.

Concrete example: Suppose your opponent controls a 4/4 creature with flying and trample. You cast Ovinize (an effect that makes it a 0/1 and causes it to lose all abilities). That creature immediately loses both flying and trample. It can no longer fly over blockers or deal excess combat damage to the player, making it much easier to deal with.

This rule is grounded in CR 113.1 (defining abilities), CR 702.1 (keyword abilities are a category of abilities), and CR 613 (layer system, where such effects are applied in layer 6 for ability-removing effects).