offensiv
attacking
In sports, focused on attacking and scoring goals or points.
Der Trainer wählte eine sehr offensive Aufstellung mit drei Stürmern.
The coach chose a very attacking lineup with three forwards.

offensive
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attacking
In sports, focused on attacking and scoring goals or points.
Der Trainer wählte eine sehr offensive Aufstellung mit drei Stürmern.
The coach chose a very attacking lineup with three forwards.

Careful: 'offensiv' does not always mean the same as the English word 'offensive'. While 'offensive' usually means 'beleidigend' (insulting/offensive), 'offensiv' in German often simply means 'attack-oriented' or 'proactive', especially in sports or discussions.
Die Mannschaft spielte sehr offensiv, um ein Tor zu schießen.
The team played very offensively in order to score a goal.
The meaning of 'offensiv' depends strongly on the context. In sports, it is about attack; in a discussion, it is about a proactive stance; and only in the case of hurtful behavior does it mean 'offensive' or 'insulting'.
Seine offensive Spielweise ist riskant, aber oft erfolgreich.
His attacking style of play is risky, but often successful.
In a sports context, 'offensiv' describes a tactic or style of play that is focused on attacking. Typical combinations are 'offensiv spielen' (to play offensively), an 'offensive Aufstellung' (attacking lineup), or an 'offensiver Spieler' (attacking player).
Der Trainer entschied sich für eine offensive Taktik.
The coach decided on an attacking tactic.
In the meaning 'challenging' or 'proactive', 'offensiv' is often used as an adverb. It then describes the way someone acts or communicates, e.g. 'ein Thema offensiv ansprechen' (to address a topic proactively) or 'eine Meinung offensiv vertreten' (to express/defend an opinion assertively).
Sie hat das Problem im Teammeeting offensiv angesprochen.
She addressed the problem proactively in the team meeting.
aggressive
'aggressiv' and 'offensiv' can both mean that someone does not remain passive, but moves forward or applies pressure. The important difference is the tone. 'aggressiv' often sounds negative: someone seems hostile, threatening, or too harsh. 'offensiv' can be more neutral and often means that someone actively attacks or boldly pushes forward, for example in sports. In conversations, the two words can seem similar, so they are easy to confuse. If the manner is hurtful or threatening, 'aggressiv' fits better. If the main point is active action rather than defense, 'offensiv' is more precise.

Die Mannschaft spielte in der zweiten Halbzeit offensiv und suchte schnell den Weg zum Tor.
The team played offensively in the second half and quickly looked for ways to goal.
Sie sprach so aggressiv, dass sich mehrere Kollegen unwohl fühlten.
She spoke so aggressively that several colleagues felt uncomfortable.