极

极 (jí) means 'extreme' or 'to the highest degree.' In everyday Mandarin it functions almost entirely as an intensifier, and learners meet it first in the pattern 'adjective + 极了' — 好极了 (hǎo jí le, 'great!'), 累极了 (lèi jí le, 'exhausted'). This post-adjective use is colloquial and warm, similar to English 'super' or 'really.'

Placing 极 before the adjective (极好) is grammatical but sounds formal or written, like 'utterly good.' 极 also carries the older noun sense of 'pole' or 'extremity,' surviving in compounds such as 北极 (North Pole), 南极 (South Pole), and 极限 (limit). Unlike 很 (hěn, 'very'), which is mild and almost neutral, 极了 marks a true peak — speakers reserve it for genuine emphasis, not casual filler.