Shannon O'Hannan Public School Puzzle Contest Winner 2019

This puzzle won the Shannon O'Hannanan Public School's Puzzle Club contest. As the prize, we are letting the winner type out his puzzle on the Puzzling Stack Exchange for all of you to solve. Our winner is Simon Swive (Grade 6).

The answer to the puzzle is a noun:

11 22 33 44
55 66 77 88
99 1010 1111 1212
1313 1414 1515 1616
1717 1818 1919 2020
212121 2222 XY


It should be noted that how the groups of numbers are arranged is irrelevant, so long as the spaces are maintained (they can technically be grouped in any way). The grouping chosen was designed to help you solve the puzzle.

It has several accepted synonyms. You can say it in a sentence, like:

"My son is a _________".
or
"Does your little girl have ________?"

• I don't believe that the "decanting-problems" tag is correct. Excellent puzzle for a 6th grade student by the way - welcome to Puzzling.SE! – Brandon_J Jan 18 at 1:35
• done - edited tags – Omega Krypton Jan 18 at 1:39
• is the word the same in both blanks or is it pluralized? – Will Jan 18 at 2:40
• I'd just like to point out that I'm fairly certain that this school does not exist. - see here – Brandon_J Jan 18 at 18:00
• Still no one knows the answer? – iminiki Mar 16 at 8:19

Down Syndrome? It's the result of having three of chromosome 21.

• No :) but you're on the right track – Vranvs Jan 18 at 1:58
• So you know the answer? Also, I updated my guess. – Brandon_J Jan 18 at 2:07

Human?

Because

all of the numbers are doubled except 21 which is tripled. The 21st letter is U.
XY is the chromosome pattern for a male, or man.
Thus... U-man or human

• No, but close... on the right track :) – Vranvs Jan 18 at 1:58
• @Vranvs how do you know the answer definitively? – Will Jan 18 at 2:32