underside
n.the side or part of something that faces the ground or is hidden underneath. You often look here to find things that are tucked away or out of sight.
n.the bottom or lower surface of an object, typically the part that is hidden from view or directed toward the ground.
“The mechanic checked the underside of the car for rust.”
“If you flip over the leaf, you might find tiny insect eggs attached to the underside.”
“The documentary explores the dark underside of the fashion industry, revealing the systemic exploitation that occurs behind the glamour of the runway.”
Often used with the preposition 'of'. Can be used figuratively to describe the hidden, unpleasant aspects of a situation.
“Fernandes sent Mbeumo through to score a looping goal that went in off the underside of the bar with eight minutes remaining.”
“Adeniran fired off the underside of the bar and Celtic defended with four centre-backs as Liam Scales and Dane Murray came on to join Trusty and Cameron Carter-Vickers.”
From under- + side.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.