“快回去，迷林被抢了！”大蝎的眼珠差一点弩出来。迷林似乎是一切，他的命分文不值。
老舍，猫城记, p.47 (see also photo of original for further context; note: 大蝎 is the name of a character, and 迷林 is a kind of forest/farm on Mars)
I'm confused about:
CC-CEDICT: 弩 (nǔ) crossbow
That's not a verb, but the sentence grammar requires a verb. Maybe it should be 射, or maybe the dictionary is incomplete, or maybe it's an obsolete usage. I don't know.
Question: In 大蝎的眼珠差一点弩出来, is 弩 ("crossbow") being used as a verb?
Question: In 大蝎的眼珠差一点弩出来, is 弩 ("crossbow") being used as a verb?
The answer is yes. 弩 ("crossbow") being used as a verb at here.
最简单的句子是由主语和谓语构成，谓语通常是动词，这个动词用来表示主语的状态，比如 牛跑了 ， 风扇停了， 他渴了 等，显而易见，在这里只有弩出来(*出来)表示动词.
分析大蝎的眼珠差一点弩出来时，眼珠是主语，大蝎的说明是谁的(whose)眼珠，弩出来是动词，差一点表示弩出来的程度. 差一点弩出来那就是没有弩出来.
大蝎的眼珠差一点弩出来可以简化为眼珠弩出来，当然简化的时候会丢失一些相关信息，所以为了说的更清楚，需要加限定词，谁的(whose)眼珠，是大蝎的眼珠。弩出来的程度怎么样？或者说到底有没有弩出来？是差一点弩出来。
个人感觉这里的弩出来和突出来意思差不多. 或许大蝎的眼珠差一点弩出来 可以换成 大蝎的眼珠差一点突出来.
另外老舍的作品<骆驼祥子>非常强烈推荐看，因为书里面的故事在当下的中国大陆重复上演了，甚至可以说剧本都没改动，变化的只是故事的主人公的名字和主人公追求的物质东西变了，比如由人力车变为房子. 评价这部小说写的怎么样？就两个字：通透.
弩 means "to bulge or protrude" here. In both middle and modern Chinese the homophone 努 is decisively more prevalent for this meaning:
唐 唐彥謙《采桑女》詩：“春風吹蠶細如蟻，桑芽纔努青鴉嘴。”
元 李文蔚《燕青博魚》第二摺：“調動我這三尺攔關臂，努起一千條歹鬥觔。”
巴金《家》二三：“他馬上縮回了手，努了眼睛把馬弁看了半晌。”
This particular usage of 弩 (that is, used of one's eyes) seems nowhere to be found other than in 老舍's writing, but it is not without motivation. Chinese homophones that look alike often involve interchanging and borrowing in their meanings (通假) to some extent. In the case of 弩 and 努, the former appears to have acquired some of the latter's meanings by the late imperial period, apparently by mistake in the double-syllable word 努力:
《資治通鑒・漢光武帝建武五年》：“馬武爲茂建所敗，奔過王霸營，大呼求救。霸曰：‘賊兵盛，出必兩敗，弩力而已！’乃閉營堅壁。”
明 何景明《贈望之》詩之五：“去住各弩力，良覿會有因。”
Then maybe folk etymology decided that this usage is worthy of more exposure because, say, who could deny that "crossbow" pertains to "bulging"? Anyway, the result is that 弩 broke away from the shackles of one fixed word into more flexible usage by Qing dynasty:
《金瓶梅詞話》第六八回：“西門慶弩了個嘴兒與他。”
《警世通言・俞伯牙摔琴謝知音》：“伯牙全無客禮，把嘴向樵夫一弩道：‘你且坐了。’你我之稱，怠慢可知。”
Takeaways:
Poetic license: “having the shape of a crossbow, bulging forward"
弩：瞪：怒目直视貌
大蝎很在意迷林。听到迷林被抢的消息，他很担心，眼珠几乎要瞪出来。
