olemus
(1a) kandevahend tavalises tähenduses
Wiktionary:
1. a small, typically rectangular or round, flat, and rigid object upon which things are carried
I carefully arranged the dishes on the tray and brought it upstairs.
Make sure that tray of eggs is properly loaded.
https://en.wikipedia.org/wiki/Tray

(1b) disketi, plaadi, kasseti liikuva sööteseadisena
Wiktionary:
3. a component of a device into which an item is placed for use in the device's operations
The CD tray will not open.
The loader is responsible for placing the work on the trays for the plating machines.
baking tray
https://duckduckgo.com/?q=%22CD+tray%22&t=h_&iar=images&iax=images&ia=images

(1c) ikooni- ja teateala kasutajaliideses
Wiktionary:
4. (computing, graphical user interface, informal) a notification area used for icons and alerts
https://docs.oracle.com/javase/tutorial/uiswing/misc/systemtray.html