Display screen or portion thereof with transitional graphical user interface

FIG. 1 is a front view of a first image in a sequence of a first embodiment of the display screen or portion thereof with transitional graphical user interface according to the claimed design;

FIG. 2 is a front view of a second image in a sequence of the first embodiment according to the claimed design;

FIG. 3 is a front view of a third image in a sequence of the first embodiment according to the claimed design;

FIG. 4 is a front view of a fourth image in a sequence of the first embodiment according to the claimed design;

FIG. 5 is a front view of a first image in a sequence of a second embodiment according to the claimed design;

FIG. 6 is a front view of a second image in a sequence of the second embodiment according to the claimed design;

FIG. 7 is a front view of a third image in a sequence of the second embodiment according to the claimed design;

FIG. 8 is a front view of a fourth image in a sequence of the second embodiment according to the claimed design; and,

FIG. 9 is a front view of a fifth image in a sequence of the second embodiment according to the claimed design.

The thick, dashed hexagon and half-hexagon shown in FIGS. 1 to 3 and 5 to 7 portray environment and form no part of the claimed design.

The gradient background of the graphical user interface is claimed subject matter.

The three thin lines just outside of the circle, one of which has a single break, are claimed subject matter.

The longer length broken line showing of a display screen and the intermediate length broken line showing of a display screen boundary, are included for the purpose of illustrating environmental structure.

The shorter broken line represents an artificial boundary defining a left portion of the screen and a right portion of the screen and forms no part of the claimed design.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-4 and FIGS. 5-9 . The process or period in which one image transitions to another forms no part of the claimed design.