A sideways movement.
A furtive advance.
In the intransitive sense often followed by up: to (cause something to) advance in a coy, furtive, or unobtrusive manner.
To (cause something to) move sideways.
The tip of the toe.
To walk quietly with only the tips of the toes touching the ground.
Standing elevated, on or as if on the tips of one's toes.
Moving carefully, quietly, warily or stealthily, on or as if on the tips of one's toes.