This is the 7828th most frequent Chinese word.
险要
Dangerous and strategically important.
险要 in this sentence expresses the steepness and danger inherent in the geography of the mountainous area, highlighting the challenge it poses for travelers.
这个山区地形险要，行路十分不便。
The terrain in this mountainous area is treacherous, making travel very inconvenient.
险要 here describes the advantageous and strategically challenging aspect of particular terrains useful for defensive purposes.
古代城堡常选址于险要的地势以便于防御。
Ancient castles were often situated in strategically challenging locations to aid in defense.
险要 in this sentence refers to the strategic importance and defensibility of the stronghold in a military context.