Semantic Superpower

A power that that is loosely defined and thus capable of a great deal of stretching what it is capable of. An example would be a hypothetical power of 'Pushing' being used to 'push' people at massive speed in order to fake teleportation, to push concepts or to push away attacks.

Examples of Semantic Superpower include:

Anime and Manga

In Maken-ki!, this is how Celia's "reverse" power works. Normally, she just uses it to reverse someone's momentum when they attack her, and for a while everyone assumes that's all she can do. However, she can also reverse a fighter's strength (making them weak), reverse the Determinator's aggression (turning him into an apathetic mess) and reverse her own gender (turning her from her natural male gender into a girl).
It's common in One Piece for Devil Fruit users to not have any obvious limits to their powers, though many of them fall into Heart Is an Awesome Power. In fact, it's stated that one of the true marks of a strong fruit user is how much experience they have with their powers and by extension, how many of these uses for their powers they can figure out.
- A good example is Kuma, alluded to in the trope description, who has the power to repel things. He often uses this to repel attacks, but it turns out he can repel the pain from a person's body, or send someone basically anywhere in the world they can travel to via a straight line. That straight line limitation is only as far as one can guess.
Aphorism is literally this. All the powers of the characters are based on a single kanji. Someone with the character for "flame" can produce flames, for example. It's even possible to change your power by interpreting that character differently.
The "hundred power" possessed by Kotetsu and Barnaby in Tiger and Bunny is said to increase their abilities a hundredfold. They primarily make use of the considerable boost this gives to their strength, speed, and ability to resist injury, but Kotetsu is also shown using it as a Healing Factor and to enhance his senses when needed.

Comic Books

Mirror Master, one of The Flash's enemies, can do just about whatever the writer can imagine as long as it involves light and/or glass, up to and including creating entire mirror universes.

"I can use a mirror a thousand different ways. Can turn a man inside out. Cut a hole through a seven-foot concrete wall. Make ye see things from yer fantasies--or from yer worst nightmares."

—The Flash vol. 2 #212

Cypher of X-Men, whose only power is the ability to understand all languages. After being written as completely useless 99% of the time, writers upgraded his powers to include programming languages and a dozen other things most sane people would never label a language.

Literature

In The Inheritance Cycle, this is basically how the Ancient Language works, with skilled/imaginative magicians able to perform feats using words that have no obvious relation. For example, Selena was able to use the word for "heal" to perform Psychic-Assisted Suicide, by "healing" people of their will to live.

Video Games

Yukari Yakumo of the Touhou series is pretty much the embodiment of this trope, in Fanon at least. Her power is, as stated in the manual, manipulation of boundaries, which doesn't sound too great until you realize that "boundary" is meant in the most metaphysical way possible. By tweaking things like the boundaries of life and death, reality and fantasy, possible and impossible, etc., she's basically God. In theory. In practice some boundaries are hard or impossible for her to manipulate, though which ones is incredibly vague (it doesn't help that Yukari can also use magic).
- Suika has the ability to manipulate density. This lets her change size, transform into mist, create mini-Suikas and black holes, and cause people to sub-consciously gather for a feast.
In the Spellcasting series, the UPPSSY spell turns anything into its opposite, broadly speaking. For instance, it will turn a two-by-four into a four-by-two, a jellyfish into a peanut butterfish, a crooked casino into a straight casino, or a flat-chested girl into a big-busted girl. Likewise, the RATANT spell turns a spell into similarly-sounding but vastly different spell, such as turning the "spell of opposites" into "spell of opossums".

Web Comics

The titular Keys of the Exalted web comic Keychain of Creation have the simple ability to unlock things, including the seals on the local Cosmic Horrors. However, according to Word of God, obtaining all five Keys grants the wielder omnipotence, as long as they can phrase the desired action as "unlocking." For example, the Deathlords are immortal, or one might say "locked" to life, and thus can be killed with proper use of the Keys.
Parodied by 8-Bit Theater: Red Mage is constantly showing his companions One Stat to Rule Them All versus a Dump Stat. Lockpicking can be accomplished, for instance, using the pickpocket skill because it's just removing a lock from a pocket in a door. The interrogation skill is simply emptying pockets of information in people's minds. This being 8-Bit Theater, Insane Troll Logic is completely applicable if you're stupid enough to not wonder how it's at all possible. Likewise, Thief can steal things that are intangible or that don't exist, basically doing anything as long as can be called theft.
The Kayoss Royal Family in L's Empire are all granted a single word. Any definition of that word is available to them as a power. The current king has the power of sound; so he can control sound waves, make whatever he says perfectly believable, and put anything into a perfect (sound) state.

Western Animation

On Batman: The Brave and the Bold, Aquaman can his power to telepathic connection with fish to control silverfish. Which are insects. Ryan Choi lampshades it.