What is the logic behind the word "lithe"?

[doctorfate]

The Free Dictionary defines the word in the question as follows:

lithe​

(līth)
adj. lith·er, lith·est
1. Readily bent; supple: lithe birch branches.
2. Marked by effortless grace: a lithe ballet dancer.

I've looked through other dictionaries and some of them say that this word only applies to things that have the ability to flex or bend easily into whatever shape someone wants them to. Others say that lithe has the connotation of "flexible, supple and thin" After doing some contemplation, I've come to the conclusion that this word has the meanings of "easily flexible" and "a young healthy, perhaps athletic, person characterized with the ability to contort and bend their body with fluid graceful movements". Am I wrong in my assessment?

 

[5jj]

I've looked through other dictionaries and most of them say that this word only applies to things that have the ability to flex or bend easily into whatever shape someone wants them to.

Few dictionaries at Onelook.com claim this, Some, like Collins, give the examples only of the word used of people.

But The Free Dictionary not only has the meaning of "easily flexible" but also the meaning of "a young healthy, perhaps athletic, person with the ability to contort and bend their body with fluid graceful movements". . Am I wrong in my assessment?

You appear to have added your own words to the definition you quoted.