Correct spelling, explanation: truly is a word with a long history as it already existed in Old English, in which it had the forms trywe and treowe, and meant loyal. The words also appeared in German and Dutch and over time they changed their forms to the adjective true and the adverb truly. Today truly can be used in both formal and informal contexts.

Definition of truly:
1. adverb – in a sincere way, really,
She truly believes that she can run the marathon, but I think she hasn’t trained enough.
2. adverb – to emphasize that what we say is true,
Bungee jumping was a little bit terrifying, but it was also a truly unforgettable experience.

Expressions with truly:
A few popular expressions with truly are: truly great, really and truly, and well and truly.
They are truly great players so it’s no wonder that they became the champions of the world.
I really and truly expected that it would be a great movie, but I actually fell asleep.
It’s late, but I know him and I’m sure that he will be on time well and truly.

Incorrect spelling, explanation: truly is a short word, but it causes some problems when it comes to its spelling. The reason for that is the fact that truly comes from the adjective true, which has an -e letter at the end and a number of English users think that truly features the -e letter too and they spell the word as truely, which is wrong.

Incorrect spelling

Incorrect spelling

Incorrect spelling