foothold
1. [ noun ] (military) an area in hostile territory that has been captured and is held awaiting further troops and supplies
Synonyms: beachhead bridgehead
Examples:

"an attempt to secure a bridgehead behind enemy lines" "the only foothold left for British troops in Europe was Gibraltar"

Related terms: combat_zone beachhead airhead
2. [ noun ] an initial accomplishment that opens the way for further developments
Synonyms: beachhead
Examples:

"the town became a beachhead in the campaign to ban smoking outdoors" "they are presently attempting to gain a foothold in the Russian market"

Related terms: accomplishment
3. [ noun ] a place providing support for the foot in standing or climbing
Synonyms: footing
Related terms: support toehold