Synonym and Cinnamon are easily confused words.
The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway.
Autocorrect suggests words that start with the same letters. It suggests what word you may want to save time, but quite often, its suggestions couldn’t be more off base and produces humorous results.
Synonym (pronounced “sin-no-nihm”) is a noun and a grammar term. It means a word that means the same thing as another word.
Cinnamon (pronounced “sin-nah-mihn”) is a noun. It means a rusty brown colored spice noted for its warm, aromatic fragrance and sweet flavor. Cinnamon added to brown sugar, gives sweet potato and pumpkin pies their flavors.
The following story uses both words correctly:
Cecil was competing in the preliminary round of a baking contest. He was making scones when his assistant pointed out they had no cinnamon in their workstation and it was too late to hunt some down now. “What about cardamom? I see cardamom in here,” his assistant asked. “No, cinnamon and cardamom are not synonyms. Keep looking,” Cecil said, curtly.