How to understand the conception"Low Profile"

Hi ,everyone.

I am an engineer on baseatation antenna. Now I read some papers from IEEE.
There is a conception which puzzle me. That is "Low Profile antenna".
I find there is no clear definition in the book.

So I seek for help on this forum. In our China, the Chinese meaning is "低剖面",But it is still not so explicit.

Can someone give me some help? Give me some authoritative books or some papers which give the explict conception, Thanks very much!

http://www.orbanmicrowave.com/The_Ba...h_Antennas.pdf

Balanced low profile hybrid antenna

Applications for low profile two way satellite antenna system

There is no particular definition, but generally the dimensions of this kind of antennas are smaller than λ/4.

dimensions of this kind of antennas are smaller than λ/4?

What dimension? For example, Why microstrip antenna can be called Low-profile antenna, but normal dipole(1/2) can't be ?