Correct spelling, explanation: the word boarded comes from Germanic languages, in which it had the form bord, but later it was also influenced by the French language. Today it is a regular English verb, which means that to the base form board an -ed ending is added. The word boarded is used in both spoken and written language.

Definition of boarded:
1. verb (past and past participle form) – to get on a plane, train, or ship,
The passengers boarded the plane an hour ago.
2. verb (past and past participle form) – to pay for staying at someone’s house for a while,
On holiday we boarded with some local family, which saved us quite a lot of money.
3. verb (past and past participle form) – to study at a boarding school, which means you not only study there but also sleep,
I missed my family the whole time I boarded at high school.
4. verb (past and past participle form) – to leave your pet at some place when you go away for some time,
We boarded our dog when we went on holiday last year.

Collocations with boarded
Boarded appears in a phrasal verb – board up, which means to protect your door or windows with wooden boards:
A few acts of vandalism have appeared in the neighborhood recently so he boarded the windows in his shop.

Incorrect spelling, explanation: both learners and native users of English tend to omit the letter -a in the word boarded, which gives an incorrect form borded. The form might look simpler, but is wrong so make sure you do not make this common mistake next time you spell the word.