Teammate

n.kind, capableeveryday

What it means

A fellow member of a team who shares work, risk, or a desired result.

Reach for it when referring to a peer whose contribution is tied to the same collective effort

Her teammate covered the briefing while she repaired the damaged sensor.

playful
sidekick
when affectionate humor about a close helper is welcome
not when Sidekick makes the relationship unequal and can diminish a capable peer.
everyday
coworker
when working for the same employer is sufficient
not when A coworker may never collaborate with the person being described.
everyday
fellow player
when the sports relationship needs to be explicit
not when This phrase is clumsy outside sport and says little about mutual support.
warm
ally
when support in a disagreement or cause is the point
not when Allies may cooperate temporarily without sharing team membership.
warm
partner
when two people share close responsibility for a task
not when Partner implies a paired or equal relationship that may not fit a larger team.
professional
collaborator
when active co-creation matters more than formal membership
not when A collaborator can be external and involved in only one part of the work.
professional
colleague
when shared employment or professional setting matters
not when Colleagues can work in unrelated areas and need not pursue the same immediate result.
literary
comrade
when solidarity through a shared struggle suits the context
not when Comrade carries political and military associations that can overwhelm ordinary praise.

supportive teammate
A supportive teammate gives useful feedback before the public review.
former teammate
Her former teammate returned to coach the junior squad.
trusted teammate
A trusted teammate reports the missed handoff without hiding their own part.

The definition and the example on this page are written here. The dictionaries above ground which meaning is being described, not the wording.