How to tell someone you're depressed without saying it?

Slowly in depth explain your feelings. Saying you're depressed straight up isn't wrong and usually gets the point right away

Get that sad look on your face. Importantly be nice to that specific person and ask forgiveness intentionally and rapidly until they figure out that something's wrong with you. Don't cry or anything. Just say stuff that has no meaning and sometimes say stuff that Shakespeare would say. They'll definitely ask you "is everything ok?"

Tell them! There is no point of hiding it and no other way to let people know. most of the people in this world are not mjnd readers!

Give them hints by acting depressed, or maybe write it down and give them (the person who you're telling) it

you could try to say that you havent felt happy for however long you have been depressed

I lost interest in my hobbies. I can't concentrate on anything anymore, and everything in my life right now is weighing me down. I'm lost, and confused. And it feels like a dark cloud is surrounding my mind, following me wherever I go, always there... making me sad and lonely.

I'm not feeling too well. My mood is a little down right now. I don't have any energy or motivation.

You can tell them what is going on in your life in order to give them an idea of the way that you are feeling

You could write them a letter, send them a text, email. Give them a clue like maybe show them a video about depression or a book so they might catch on?

It's likely that if they know you well enough, they already have there suspicions. You could try and trigger them to suggest it, simply by telling them what is bothering you, making you stressed or anxious or sad. You could alternatively write to them, whether it be a text message or a letter. If you are not wanting to discuss it in person, you can kindly ask that they write you back in the same way, and tell them that you feel uncomfortable speaking about it in person.