Plain and Upfront

Plain adjective - Free from all additions or embellishment.

Upfront and plain are semantically related in straightforward topic. In some cases you can use "Upfront" instead an adjective "Plain". informal substitute

Nearby Words: plainly, plainness, plaint

Upfront adjective - Frank and honest.

Plain and upfront are semantically related in honest topic. Sometimes you can use "Plain" instead an adjective "Upfront", if it concerns topics such as open, truthful, straightforward.