せっきん接近sekkin
1.

The act of moving from a state of separation to one of proximity, whether physically or metaphorically, such as a storm approaching land or two parties bridging the gap between them in capability.

2.

The process of forming a relationship or increasing familiarity with someone, denoting the transition from distance to interaction in social contexts.

Example:

飛行機はニューヨークに接近している。

せっきんせん接近戦sekkinsen
1.

A form of combat occurring at very short distances, where fighters engage directly and use hand-to-hand techniques or weapons suited for close-range encounters.

2.

A type of physical confrontation that involves grappling, striking, or the use of melee weapons, emphasizing proximity and quick reactions between adversaries.

3.

A tactical style of fighting characterized by the need for fighters to maneuver closely to their opponents, often leading to intense and immediate exchanges of force.

きゅうせっきん急接近kyuusekkin
1.

A swift progression towards someone or something, often implying an increase in closeness or urgency in the relationship or situation.

2.

An abrupt surge in emotional or physical closeness, frequently resulting in a heightened sense of familiarity or tension between individuals.